First Time to Italy & Europe

1. Buy point-to-point for these trips. No eurailpass.
2. Worth it if you visit a lot of museums.
3. Take the ferry to towns along the lake. Must-sees are very subjective.
4. Check trenitalia.com for train info. The only way to avoid crowds is to be there before 9am, but it's a very big space and you should be okay even later in the day. Or get there later in the afternoon, since you are traveling such a long distance. The Basilica closes at 7pm. Next best thing depends on what you want to see.

1. For the day trip to Rome, I would like to take the earliest train in the am, so that I can get to St. Peter's before the crowds. What is the earliest the trains leave Florence and would that be early enough to avoid the crowds? After St. Peter's, is there a next best thing to do?

Using the Trenitalia website (http://www.trenitalia.com/tcom-en ), picking a random date (July 25), and Firenze S.M. Novella> Roma Termini, it looks like your best bet is a 6:50 train that will arrive in Roma at 8:35. This is not the earliest train but it's the fastest of early trains (1 hr/45 minutes) and will arrive just 9 minutes later than the 5:50. (2 hrs/36 minutes). From Termini, either walk or take the metro to St Peter's.

You will not miss the crowds at the Basilica, however. It's high season in Rome so the top attractions are BUSY almost all the time.

After St. Peter's, is there a next best thing to do?

What else do you want to see in Rome? I might suggest spending some time with a guidebook to see what appeals to you?The Vatican Museums/Sistine Chapel? Galleria Borghese? Colosseum? Other of Rome's churches? Piazza Navona? Trevi Fountain? You do need to make advance reservations/tickets for some of these attractions - like the Colosseum and Vatican Museums/Sistine - to avoid wasting a lot of time in very long ticket queues so it's important that you do that right away if those end up on your list

Is there a reason you are recommending Trenitalia? and not RailEurope.com? RailEurope looks like it is a lot cheaper? Is there something wrong with it?

Customs is not what takes time when you arrive in Rome. It's Immigration/Passport Control; and at FCO in high season, the lines may be long. You'll see lines for non-EU citizens. That's you. After your passport is stamped, you'll see the signs for Customs. Presumably you go through the "Nothing to Declare".door. (You're only bringing things for your personal use, right?). Ordinarily no official even asks.
Venice is a small airport, especially compared to FCO. There is no "Customs" when you depart. You check in and your passport gets stamped again, showing that you did not overstay your allowed tourist time. Just FYI, that's 90 days, assuming you're a U.S. citizen.
Take a deep breath. Try to relax. Have a great trip.

RailEurope ia a US web site that sells tickets and passes. Trenitalia is an actual railroad. Most of time RailEurope will show higher prices since they markup the local provider's tickets. Another Italian rail service is Italio.

http://www.italotreno.it/en

Forgot to add. Unless you have something to declare customs is just a formality, just walk through the proper door. Takes five seconds. Passport control is the longer process. If you enter the Schengen zone in Rome then you will need to go through passport control. Likewise you will go through PC on the way out of the Schengen. So if you fly Venice nonstop to the US passport control will be in Venice. If you connect to another Schengen country, PC will be there.

With the trip so near its probably too late to rearrange your trip to do Rome when you arrive there.

Making 3 trips trips between Rome and Florence, rather than one has sadly stolen half a day of vacation to just ride the rails between Rome and Florence

What day of the week do you plan to go to St Peters? On Wednesday, usually, there is a Papal Audience, drawing thousands extra there in the morning. What to do after St Peters depends on how long you choose to visit there. I have arrived there at 8AM for the Papal Audience and left at 430PM after climbing the Dome and touring the interior of St Peters. Some people are in and out in 30 minutes.

Most/many would likely suggest seeing the Colosseum, and for good reason, as a 'next best thing', after St Peters.

Is there a reason you are recommending Trenitalia?

As Rocket said, Trenitalia is Italy's national rail service. RailEurope.com is a 3rd-party booker that marks up the prices so I wouldn't use them. Frankly, I'd be very surprised if you're seeing cheaper tickets on that one versus Trenitalia. Anyway, always purchase 2nd-class tickets as the difference between those carriages and First or Business Class isn't enough to warrant paying a much higher price. My guess is that, at this late date, the very lowest-priced super economy and economy tickets are already sold out but you'll have to check the website.

Italo is private Italian rail service that can also be a good resource if traveling between major cities, such as Rome to Florence or Florence to Venice. I didn't include that one in my response to the question about earliest train from Florence to Rome as Trenitalia can get you there earlier. You could, however, take an Italo train BACK to Florence if they offered a more attractive price.

You don't say where exactly your villas are on Lake Como or Florence. Do you know if both are IN a city and can be reached without a car? You also don't mention the ages of the 5 in your group: are there any very young children or elders with mobility challenges?? That can affect the attractions you choose and how you get around.

With the trip so near its probably too late to rearrange your trip to
do Rome when you arrive there.

Yes, it probably is too late and a shame because it would have made more sense to put your Rome time on the FRONT end of the trip versus heading directly to Florence and then RETURNING to Rome just for a day. This added time and money for 2 train trips that could have been eliminated. There is also a great deal to see in Rome so I wonder that you've only planned 1 day for that one?

Rome is so massive, I cannot comprehend doing it as a day trip. Especially with the Vatican, which is a four hour tour after the wait. It's four hours of total transit, four hours at the Vatican, four hours for something else. It's a brutal day, imho, in Rome, which can be a bit hard on the traveler to start with.

I love Rome and I love the Vatican like the good atheistic art and culture lover that I am. But I can't see enjoying it in the manner. That's my thought. You CAN do it, but do you really want to do so?

I have never ridden a train.

I think you could benefit from https://www.ricksteves.com/travel-tips/transportation/trains and https://www.seat61.com/Italy-trains.htm

Is the Venice Airport a very busy airport?

Read about it here http://europeforvisitors.com/venice/articles/marco_polo_airport.htm

Could you give us the exact address of these villas? Como is a city. Lake Como is a large lake. Where exactly is your villa? Villa in Florence or near Florence?

Trains don't go everywhere.

Rome and Venice in a day each is too short. If you land in Rome, it would make sense to spend a few nights there first rather than commute for a day from Tuscany. Florence to Rome is 200 miles each way. The high speed train takes only 90 min but how far is your villa from the station in Florence?

I like staying in one location for a week and using that as your base, however you lost me when you talked about a day trip to Rome and Venice. I would prefer to absorb where I am and relax and maybe leave Rome and Venice for a future trip. If you are dead set on a day trip to Rome maybe a bike tour for the family that would give you a good overall view of the city and depending on the age of your children leave a more positive impression of the city than standing in line and sitting on the train.

I cannot recommend the app for Trainline.eu enough. Same price as the train companies website and so very handy. We used it for our trip to Italy last month. You won't need to print or validate tickets.
We flew out of Venice three weeks ago and though it is small ish, it's extremely busy. It took all of the 2.5 hours we were there to get to our gate. We flew American to Philadelphia.

I would not walk from Termini to St. Peters. Take a cab for 15E and they will drop you off right at the entrance.

Re: bike rentals in Roma, outside of riding through the Borghese park which you can't do in the time you have, I was in Roma for 12 days and saw many people who paid for the privilege of walking their rented bikes through the city. Bikes share lanes with cars, trucks, taxis, buses, motorcycles, and other bikes.

I'm with Zoe: other than riding Villa Borghese or out on the Appia (and I do mean OUT, far enough away from the busier, closer-in section or on a Sunday when it's closed to traffic), I wouldn't personally bike in Rome.

I also wouldn't personally take a cab to the Vatican from Termini when the metro is right THERE in the station when you get off the train: take Metro A to the Ottaviano stop, and use a map to walk from there to the basilica. A day-tripper could also benefit from buying a 24-hr day pass (€ 7,00) at Termini which will allow unlimited rides on public transit all day. For example, getting back on the Metro, they can take it to a stop near the Spanish Steps (Spagna stop), and/or back to Termini and switch to Metro B down to the Colosseum/Forum/Palatine and San Clemente (Colosseo stop). The metro doesn't go everywhere but gets close enough to some of the biggies for the day tourist in a bit of a hurry.

This is the link to the company that provided our guided bike tour of Rome in September.
http://www.topbikerental.com/nuovosito/eng/rome-bike-tours.php

We did not have to walk our bikes at all and we were able to cover a lot of territory in a couple of hours. My husband and I are in our mid 60's and fit but we were at least 15 years older than anyone else on the tour and we were able to keep up and negotiate the streets with no problems. We have done bike tours in many European and US cities and it is our favorite way to get an introduction and overview of a new city and then we can decide what we want to go back and visit on our own.