Rent a car or take train/bus?

First I hope you get lodging reservations Asap as Aug is peak travel in Italy. I suggest you only have a car in Tuscany and if you do see more than just Volterra. Driving from Rome will be terrible and into Florence just as bad. If you do get a car for sure rent it at airport or train station but away from central florence and rome for sure. You can take a bus(cheap) or train from Rome to Pompeii easily.
Too bad bus to Volterra is difficult but it can be done with transfers and limited buses schedules if you are so inclined. Me I would opt for a car jsut for Tuscany.

If you want a car, I suggest you take the train from Rome to Orvieto, then pick up your car there. DO NOT drive in Florence. I returned my car at the airport and took the express bus to town. It costs 5€. If you don't plan to go to any hill towns besides Volterra I would not rent a car, but explore other ways to get there. If you drive, each driver will need an International Drivers Permit (IDP), available at AAA for $15. Be sure to read about the ZTL zones. You can do a search on this site. You will most likely save money if you buy point to point train tickets, as opposed to a rail pass.

Kim, To begin with, I agree with the previous reply concerning accommodations. You'll be travelling in PEAK season, so it's going to be hot and crowded. If you don't have bookings now, you could have problems finding somewhere to stay. As this is your first trip to Italy, are you aware of the usual "caveats" on driving there? Each driver will require the compulsory I.D.P., and you'll have to be EXTREMELY careful to avoid ZTL areas, or you'll get a nasty surprise in the mail several months after you return home. If you need more information, post another note. I don't know if this is a factor in your case, but if you're under 25, there may be "restrictions" on renting a car. With careful planning, it is possible to travel to each of the locations you mentioned by public transit. Here's a few comments on each trip.... > Rome to Pompeii: this will be a LONG day! You'll travel via Trenitalia to Napoli Centrale, and then Circumvesuviana from there to Pompeii. > Rome to Volterra: One method to consider would be train from Roma Termini to Cecina or Poggibonisi. From there to Volterra, there should be Bus service but I'd have to do some more research on the specifics. An alternative would be to travel by train to Siena and rent a car there. At the end of your visit, either return the car at the Florence airport or back in Siena. DO NOT drive in Florence!!! From Siena it's an easy ~1H:30M by Bus or train to Florence. If you decide to go by train and it's a Regionale, DON'T forget to validate! Happy travels!

Thanks to all for the help! We do have our hotels reserved, we just need to determine the best way to get the the places we are staying. We appreciate the advice.

As pointed out above, do NOT get a railpass unless you've done the math first. 95% of the time it's less expensive to get point-to-point train tickets. You can save a good bit by getting the discount tickets in advance through trenitalia.com, but be aware that those are nonrefundable. Happy travels.

We have traveled in those areas and I love to rent a car over public transit. However, you don't want a car in Rome or Florence. We stayed in Rome and only rented a car when we were leaving room. We drove to Florence and parked the car for the time we were there. We also made the drive down to the Amalfi coast and Pompeii. I liked the drive but traffic was bad and parking is not fun. Although I love to drive you may be best taking the train for the places you are going.

I'll represent the tree huggers. Using public transportation is better for the planet. Your trip is easily done by train and bus.
The train station nearest Volterra is Saline di Volterra. It's a short bus ride into town. Have a great trip!

Just got back from 3 weeks in southern Italy and Sicily with sister and nnephew. We landed in Rome and after a few days travelled by train to Salerno to explore amalfi and paeteum. It was only at that point we rented car which was great and gave lots of freedom to explore basilicata, Calabria and Sicily outside cities. Drive to Sicily and ferry was great but traffic is horrendous on A3. I am glad we did it, and I got used to Italian driving style quickly, but def not for the faint hearted. We needed car to visit somewhat remote villages to see family. In general, I recommend avoiding car rental unless you are off main public transit routes and only do so for short stints unless you feel real need to get out on the road. Read up on Italian driving style rules and maintain a calm mind and a sense of humor

I agree that you do NOT drive in Rome or Florence. However, driving in Tuscany, in my opinion, is the way to go. I have driven all over Lazio, Umbria, and Tuscany without a problem. I did drive in Florence, once, never again. So, I drop the car at the airport. It is also easy to rent cars at the airports and it is much easier to be on your way for that location.