Public Transportation vs Rental Car

You will not need a car to get around in Rome, Venice, nor Florence. It can all be done with public transit or on foot. In addition, getting from one place to another can all be done via trains. If you are going the Amalfi Coast just to see and enjoy the scenery, the driver will probably not be able to do either. That can also be done by train and / or a tour of some type. If possible, try not to fly out of Rome -- try Milan or Venice so as to not waste time back tracking. Trying to do what you want using a rental car will, in my opinion, be a great big pain in the anatomy. Others will have different opinions, but I'd not try it and we've been to Italy a number of times. Just food for thought.

More than the roads or actual driving is the ZTL ; have you read up on that. It is not like cities in the US where you can drive where you want. In Italy the cities have roads that can only be driven on by local residents and commercial vehicles, much like we have resident only parking in cities, they have resident only driving.
Hotels in these cities cannot be reached by car without driving on these resident only roads.
You could end up with thousands of Euros in fines if you don't research before going.
You cannot drive into Rome where your hotel is most likely unless you get some sort of special pass from the hotel and if you deviate at all from the road plan provided you will be fined hundreds of Euros by mail after your vacation.
You cannot drive into Florence, same as Rome.
In both of these cases if your hotel does not offer this type of special pass for coming and going, maybe a paid garage in the city will if reserved in advance.
Expect to pay very high prices for parking the car each day, probably 40 euro per night average for these areas.
Venice is an island so you cannot drive to Venice. You could drive outside of Venice and park in a pay lot but still have to get your heavy luggage to your hotel. Even if you opt for the pricey private water taxi, which you should you still need to be able to carry your own luggage from your car parking area to where a water taxi may be so you need to be able to walk a bit with your own bags for a car and Venice.
Also even the private water taxi may not be able to go door to door depending on your hotel, you could wind up with a walk after the taxi to the hotel door which may or may not involve bridges to cross which are a pain with wheeled luggage.
Amalfi Coast you can drive where you want but there the roads are tough to drive and there is very little parking, what parking they do have if not full when you reach it will be very pricey.

What on earth would you see in Florence with 1 overnight ; by the time you reach Florence from Amalfi Coast you will be very tired and it will end of day, then you have to check out early the next morning to drive a good distance to Venice. Even by train it may not make sense.
Also 2 nights in the Amalfi Coast reaching it from Rome and departing to Florence or Venice is not enough time there either and makes the transport to get there not worth the time. You need 3 nights minimum, 4 would be better for the Amalfi Coast in your case.
See if you can book the airfare into Rome and out of Venice so you don't have to at the end get back from Venice to Rome as well if you keep Venice in the plans at the end.
You would enjoy your vacation much more if you limit the stops and spend a little more time in your stops of choice.
Pick 2 plus you family stop, anymore is too much. Your family, Rome and Amalfi or Your family Rome and Venice, etc...

FYI: I am not anti-car rental in Italy. I have a car booked for our upcoming trip but I am avoiding all of the cities while I have the car and returning the car while approaching Venice. Cars are good for the non-cities like your family's hometown but a major pain in the rear for the cities so you have to plan the logistics in advance and spend hours researching.
Not trying to sound rude, you are at the beginning stages of what is a time consuming process of planning such a trip.
If you want an easy trip there are plenty of tours, choosing to self plan means more work and hopefully more enjoyment in the end.

You will likely need a car for Veroli, which is a pretty town in a rural area with limited public transportation options. So unless your relatives can pick you up and drive you around, you will probably need to rent a car for that portion.
My suggestion would be to visit your relatives after (not before) your first couple days in Rome (where you definitely don't want to have a car).
So, this is my suggestion:
Arrive FCO
take taxi to Rome city center hotel, and stay in Rome for the initial few nights (2, 3, whatever).
At the end of your Rome stay, rent a car from a city location and drive to Veroli. Visit relatives.
Drive from Veroli to Amalfi Coast. Try to book a hotel which has parking or that can suggest parking arrangements with local garages, because parking in the Amalfi coast can be challenging. Stay in the Amalfi Coast (Positano, Praiano, Amalfi, whatever) however long you wish. You could also return the car in Sorrento, and stay without a car, it's up to you.
At the end of your Amalfi stay, drive to Florence. RETURN THE CAR UPON ARRIVAL. A car in Florence is not needed and actually is a hassle to have. If you already returned the car in Sorrento, then you can go to Florence by bus (to Sorrento) and train (from Sorrento to Naples to Florence)
Stay at least 2 nights in Florence, 3 nights probably better. Florence is bigger and has more to see than Venice, so if anything, you should stay 3 nights in Florence and 2 in Venice, if you don't have 3 nights each. A full day is the very minimum for Florence. If you don't even have 2 nights, that is too little time.
At the end of your Florence stay, take the high speed train to Venice (2h 5 min). Stay in Venice 2 nights.
Finally, at the end of the Venice visit, take the train all the way down to Rome.

Now, I don't know how firm your flight plans are already. If they aren't, it would be best to fly into Venice and do the exact opposite itinerary:
Fly Venice, visit Venice
train to Florence, visit Florence,
Rent car in Florence and drive to Amalfi Coast (you could also do this by train if you wish, then rent a car in naples or Sorrento).
Visit Amalfi Coast.
Drive car to Veroli, visit family.
Drive car to Rome, return car upon arrival, then visit Rome for a few days.
Taxi to airport, and fly home.

Cari.lynn,

Your trip is easily doable via public transportation. However, I would suggest flying into Rome and out of Venice. Why spend 4.5 hours on a train just to get up and catch a plane the next morning? Besides, if you didn't have to double back to Rome, you could spend an extra day in Florence.

I would suggest going to various web sites like Onedayinitaly.com, roninrome.com and almalficoast.com to start piecing this trip together. The web sites for train tickets are tenitalia.com and italotreno.it. I have taken both trains and can't think of a reason to pick one over the other.

If/when I plan a trip to the Amalfi coast region, I plan on taking the train from Rome to Salerno and entering the region from that end. Buses and ferries are the modes of public transport between towns of the Amalfi coast.

A stated in other responses, rental cars are a liability in most of Italy's larger cities. Just do a search on "ZTL" in this forum to learn why. I have been to Italy multiple times for a total of about 7 weeks and never used a car. Public transportation is just too convenient and affordable unless you're visited the back roads. If you do decide to get a car, don't forget to bring international driving permits (purchased at AAA offices in the US).

As for luggage, take Rick's advise and pack light. There are plenty of places to get laundry done and if you plan correctly, there isn't any reason why you can't live out of a carry-on size suitcase for several weeks. Sticking to one small suitcase per person will make the travel so much easier and more pleasant.

I agree about flying into Rome and open jaw out of Venice. But your first trip to Italy will likely be a blur as you're trying to see too much for the time allotted. Your first and last day of the trip will be essentially wasted, and every day you move from city to city is also a waste.
The Amalfi Coast is just under 200 miles south of Rome which makes it seriously out of the way. I'd skip it.
You should spend more than a day in Florence, as it's a very important city in architecture, history, art and otherwise. It's best if you took a train from Rome directly there (170 miles). Venice is also an important city, and it's about 150 miles NE of Florence on a fast train.
It'd be nice if you had just a little more time in Italy. Otherwise, I'd suggest you simplify your itinerary.

Cari, without taking your thread in another direction, is there any way you could postpone this trip until the fall? If I read your previous posts correctly, you are attempting to leave in 11 days - June 27th - and it doesn't sounds as if anything at all is booked yet? I'm concerned that not only are you trying to shoehorn too many places into too short a time but that there are so many details yet to be worked out.

The type of first-timer's trip you are planning usually takes months, not days. It's the research on everything from what's required to drive/park without expensive fines and frustration in Italy, to how to book and take the trains, to where to stay, to what to see and most economical/efficient ways of doing that. Trip/medical insurance is usually a must as well. Those of us who've been to Italy before could probably pull at trip off on the fly but this is a LOT if it's your first time. Have you and your family been to anywhere else in Europe before independently of a tour or at all?

I can sense that you're already frustrated, and the very short amount of time you have to put it all together isn't helping. Some additional time to relax, do some research and then create a plan based on budget, time, desired locations and advice (lots more questions on this forum!) might be a necessity for your sanity. Additionally, fall is going to be a much more comfortable time of year than summer for locations you're looking at.

Might be a long shot but worth throwing out the idea. If your dates absolutely can't be moved, the terrific folks here will do everything they can to help but it's going to be a push to wrap up in a week and some odd days.

cari,

My first impression is that you're trying to cover too many locations in what appears to be about 12-day time frame. If that's the case, I think a bit of "paring down" will be needed. My suggestion would be to skip the Amalfi Coast, as you really only have about 1.5 days there, once travel time is taken into account. Hardly worth the effort. Venice would be another possibility but I didn't suggest that as Venice is connected by high speed rail which will be the most efficient travel method and the best use of your limited time. The high speed trains travel at up to 300 km/h, so that's much faster and more efficient than a car (and more pleasant and relaxing).

It would help to know if you've already booked return flights to Rome. Especially for such a short time frame, open-jaw flights would be best (ideally inbound Venice / outbound Rome). Also, I may have missed it but when is this trip taking place?

On the topic of car rental, how old are your children? If they're teenagers, you'll need to rent a larger vehicle for four adults with luggage, which will likely be cumbersome in the narrow streets of Italian towns. You'll also need to be aware of some potentially expensive "caveats" when using rental cars in Italy.....

• Each driver listed on the rental form will require the compulsory International Driver's Permit, which is used in conjunction with your home D.L. These are easily available at any AAA office for small fee, and are valid for one year.
• As the others have mentioned, you'll need to be extremely vigilant to avoid the dreaded ZTL (limited traffic) zones which exist in many Italian towns and cities. Do NOT drive in Florence, as the city is just about saturated by automated ZTL cameras! Each pass through one will result in hefty fines, which you probably won't receive until several months after you've returned home.
• You'll also have to contend with speed cameras including the devious Traffic Tutor system which measures not only instantaneous speed but also average between two points. Violate either or both, and expensive tickets will follow. There are also tolls on the motorways, fuel pumps at unattended stations which may only accept Chip & PIN credit cards and parking charges. As you may leave all your luggage in the car at times, you'll also have to risk having your gear pilfered by thieves. Cars are better in places that aren't well served by frequent public transit, such as the hill towns in Tuscany.

Regarding your trip to Veroli, that could be done by public transit although I'd probably use a "combination" method in order to have transportation during the visit with your relatives. Assuming you follow your original plan to some extent, here's one method you could use.....

• travel by train from Roma Termini to Frosinone (about 1.5H, fare €5 PP, Regionale).
• rent a car in Frosinone. There appears to be several rental agencies there, including Europcar and Hertz. From there it will be an easy drive to Veroli. You could return the car after your family visit or carry-on, depending on where you decide to go at that point. Note that Frosinone also now appears to have ZTL areas. My Italian skills are limited so I can't decipher all of this but perhaps Roberto or one of the others can help with translation (unless you speak Italian) - http://www.comune.frosinone.it/archivio3_notizie-e-comunicati_0_1855_0_2.html
• an alternative to renting the car would be to travel by train to Frosinone and then take the bus to Veroli (about 20 minutes?). Here's a link - http://www.oraribus.com/bus_en.php?from=Frosinone&to=Veroli#autobus . If you won't need a vehicle during your family visit (relatives are going to provide transportation), the bus might be better?

There are also some potentially expensive "caveats" when using trains and other public transit. If you need more information, post another note here.

Good luck with your planning!

I have not read all the generous responses above, but will just make or reiterate these points:

A car rental might be cheaper than train for four people together, or it might not after you factor in highway tolls, fuel, and parking fees. Anecdotally, I thought that the highway tolls I paid recently were similar to the cost of a 2nd-class train ticket for the same distance.

Beyond cost, you're considering whether Italian traffic will freak you out. I anticipate that this will happen on and around the Amalfi Coast as well as if you attempt to drive into the city centers of Rome and Florence.

Given the high frequency of train departures, either car or train can be done on a very flexible schedule, without much research or advance commitment. If the idea of booking trains now for a cheaper rate is stressful, then put that on hold and focus on more critical decisions first.

Packing light will definitely make many aspects of the trip easier, regardless of what transportation you choose.

I would drop Florence (I love Florence but it is a town that takes time to explore its rich art heritage; you get nothing from one night there but aggravation).

As others have noted you don't need a car for this itinerary and it will be a pain to have it. A second observation, finish with Rome don't start there and then waste your second to last day rushing back for your flight. I'd pick either the AMalfi coast or Venice but assuming you keep those and drop Florence I suggest that. Arrive in Rome, immediately buy a ticket to Venice at the FCO train station; they will sell you a train you can make as well as a ticket to Termini in Rome. Head for Venice and spend 3 nights/2 days. Then take the train from Venice to Naples and the Circumvesuviano local train to Sorrento and spend two nights there with a day trip by bus to Amalfi. Then take the boat to Naples and the train to Rome and finish with 5 nights/4 full days in Rome and be there to fly out. The first day is shot with jet lag and logistics, so use it to get to your farthest point. This buys you a full extra day at the end instead of the rush to get back to home base. We have done it both ways and this is definitely better.

I would just head for Venice for 4 nights and then to Rome for the rest and vary your scenery with a day trip or two from Rome: Ostia Antica, Tivoli and Villa Adriana or perhaps Orvieto. The more being there versus getting there, the happier a trip IMHO.

You have 10 nights in Italy,and want to visit relatives in Veroli.
I would spend the time Rome and south. As Janet mentioned your first day is a wash. Use this to your advantage. Travel to the farthest location. Here's my path.

27th. Arrive Rome. Taxi to Roma termini. 30 min.
Train. Roma Termini-Napoli Centrale. 1 hour 10 min. (1H10m)
Purchase tickets for Circumvesuvian to Sorrento Follow signs downstairs, time is 1H07m-1H28m. Total travel time 2H37m. Sorrento has the best transportation for accessing the Amalfi Coast. Train, bus and ferry.

28th. Sorrento.

29th. Sorrento.

30th. Sorrento.

1st. Pick up rental car on Corso Italia. Try Auto Europe or Kemwel. Remember you need an IDP, to drive in Italy. Available at AAA $15.
Drive to Veroli. 2H17m. Unless the coast road is busy then it will take longer to get to the A3. Visit relatives.

2nd. Visit relatives. Drop car,
Trying to return in Rome will drive you nuts!!! Late afternoon Bus/train to Rome 1H57m.

3rd. Rome.

4th. Rome

5th. Rome. Day trip to Orvieto
1H 17 m. Or Ostia Antica. About an hour.

6th. Rome.

7th. Travel home.

This gives you...

4 nites/3 days Sorrento.

1 nite/1 1/2 days Veroli.

5 nites/ 4 days Rome.

Edit.
If you want to spend more time in Veroli, take a nite from Rome. Don't do day trip.

You will have a great trip, the things that frustrate will become funny over time.