19 days in Italy. Should we do it all by train or rent a car for some?

Your trip will be more enjoyable and cheaper if you only rent a car for destinations on your list that trains don't go to.
Trenitalia.com will help you confirm that trains go to all the places on your list. Getting to Pompei is a little different but you don't need a car to do it.

Did a similar trip a few years ago. We took trains the entire time. they were great and easy to use. We flew into Rome took a train the same day to Milan. We had added Milan to the trip after buying tickets to Italy. Spent one day in Milan, my travel buddy wanted to see the last supper. Took the train to Venice, then Florence, Cinque Terre, and ended in Rome where my friend flew home and I headed to Greece. The trains were great

Wendy

All of these listed destinations are served by train, so I also would not rent a car. From Naples to Pompeii and Sorrento is served by the local commuter train, instead of the national railway, but it is direct and frequent. Destinations on the Amalfi coast can be connected by bus, taxi, or ferry from Sorrento.

I would suggest you not add another city, but instead add time to the cities you're currently visiting – particularly Rome and Venice. Your time in both of those cities seems short. I've spent at least 2 months in Rome over various trips and more than a month in Venice, and there are still things in both cities I have not had time for. If you want more variety, you can also do day trips, such as Orvieto from Rome, Lucca or Siena from Florence, or Padua or Verona from Venice. I would also suggest allowing more time for Sorrento than the CT, since there are more unique experiences in the Sorrento area.

I agree with Sherry's advice, adding some daytrips is easy if you run out of things to do in the cities on your list.

Joan, I'd be a little concerned about landing into the Cinque Terre next month without a hotel reservation. I've seen posts from RS members who were having a bit of a time finding rooms some months ago.

I would start in Rome (no car) and possibly add a day, then take the train to Florence, stay there a few days, then pick up your car as you leave. I would spend a few days traveling Tuscany by car and staying in a small village or two. If you continue your drive on to CT it can be difficult to navigate with a car. I have done a number of trips there and one time parked at the station in LaSpezia and took a day trip in, another time stayed in a hotel in Alessandria, left car at the hotel and did a train trip in for the day. Neither of these options gives you an overnite, then you can drive on to Venice and drop car before going in to the city. Another option would be to drop you car in LaSpezia , stay in CT (if you can get a room) and take the train to Venice... only using your car for the Tuscany portion of your trip.

A car is not necessary and is just another hassle that in effect separates you from the cultural experience. As others have said, add time to Rome and Venice. You may have to settle for a room outside of the Cinque Terre: Levanto, La Spezia, etc. If you are going to do this on-the-fly, try to reserve at least the day before you arrive in a new location. Otherwise you may arrive and have to spend several hours just looking for a place.

May 9 - arrive late. Sleep in Rome (1 night)?
May 10 - morning train to Venice (3 nights, 2 days), 6-7 hours in transit door-to-door
May 11,12 - Venice
May 13 - morning train to Florence (4 nights, 3.5 days) 4 hours in transit
May 14, 15, 16 - Florence
May 17 - morning train to CT (3 nights, 2.5 days) 4 hours in transit, or more depending on town
May 18,19 - CT
May 19 - trains to Sorrento (4 nights, 3 days) This journey will take most of the day.
May 20, 21, 22 Sorrento
May 23 - morning train to Rome (6 nights, 5.5 days) 4 hours in transit
May 24-28 Rome

You don't have time for anywhere else. The time in bold is the free time you have in each place. I put Venice first because it's more laid back that Florence, better to start there. As far as travel time, it doesn't matter since you're backtracking no matter what. Time in transit is an estimate of door-to-door time, doesn't include time to check in, unpack, repack, check out.

You have chosen two destinations (CT and Sorrento) that are time-consuming to get to, and you're locked into a round-trip from Rome, so you have a lot of travel time. I suggest dropping the CT and adding the time to your other stops, especially Sorrento. You are never going to see everything, but if you slow down, you will enjoy what you do see a lot more.

Personally, I don't think the itinerary is too rushed but I'll throw my vote in with the others to use the trains instead of a car. You don't need or want one of those in the cities/towns on the itinerary, and it'll just add extra cost and hassles (parking and no-drive zones) for a vehicle you'll likely never touch during your stays.

Thank you for all the feedback. I am planning to book all hotels before we leave so if there is no accommodation in C/T we will add it elsewhere. Based on some of the feedback we may rethink that part of the trip and stay longer in Sorrento. Anytime I tell someone we are going to Italy they almost always say "OMG you have to go to Cinque Terre!!!!" This is why it is on my to do list.

We are actually leaving Vancouver on April 28 arriving London on the 29th. Staying in Ramsgate for 3 nights and flying to Belfast on May 2 for 7 nights then back to London on May 9 with a connection to Rome. So there will be no jet lag! We love to hike and walk so we should be ready to explore.

Thanks Again, Joan