Base in Tuscany advice

It’s really not a good idea to drive a car right after a trans-Atlantic flight. Instead, you could take a train to Florence, spend a couple of nights there exploring and recovering from jet lag, then rent your car for exploring Tuscany.

I usually pick what places I want to see first, then I pick a base in the middle where I don't have to drive over a certain amount per day. You will have two full days in each place--does that give you enough time to see all on your list at a leisurely pace? I think a lot of us could make a compelling case for only one base, but it just depends on the pace of travel you prefer.
I agree I would not drive nearly three hours from FCO upon arrival (unless you are perhaps in business class, which would be the only guarantee of adequate sleep for me). There are plenty of ways to reorder the trip to avoid that. You could take train to Florence and start there, then do a one-way rental back to Rome.

I completely agree with your argument against driving after flight. Will talk more with my macho 'all can do' hubby :)

As far as the base go, if I to consolidate it into one base - what would be a good small but yet with a town/ restaurants/ evening stroll flavor central place that is not overkilled by tour buses will you recommend?

Seeing that two adults in your traveling group are in their 20’s, I would replace San Gimignano with a larger place like Siena or Arezzo which I think they would enjoy much more. Arezzo could be your first location - 90-120 minutes from Rome by train. I’ve stayed in both of those towns for multiple nights, and even at 65 years old, I would prefer those to tiny SG at night. Either one paired with wonderful Montepulciano would be a great experience, especially with your finale in Rome.

Have a great time!

Volterra might be a bit less touristy

I agree that getting behind the wheel immediately after the long redeye flight from the US is usually a bad idea unless you're sure you'll be able to sleep on the plane and thus arrive rested and fit to drive.
Looking at your areas of interest it occurs to me that an alternative to your proposed itinerary might be to take the train or bus down to Siena upon arrival in Florence and then use that as your base for exploring further afield. Spending a night or two in Siena before collecting your rental would allow you to get a good night's rest before driving.
There are several rental car concessions within walking distance of the Siena train station which would make picking up and dropping off a rental pretty simple, plus there's cheap underground parking in front of the train station so you wouldn't have to worry about inadvertantly wandering into restricted driving zones. The underground lot is right on the main highway heading north & south out of town, making for easy (and short) day trips to the Val D'Orcia countryside (Montepulciano, Pienza, etc), SG, and the Chianti region.
Something like that would allow you to unpack once rather than relocating every few nights, with the added benefit of being able to enjoy Siena in the early mornings and later in the afternoons when the day trippers have departed - it's a whole different experience without the crowds.

That is a good consideration for the 20 year olds (for you all to discuss: do you want a quiet village feel or a more bustling town?) but also consider that driving in and out of a larger place means parking considerations. It's easy to work around, but you want to be well aware of ZTLS and have dedicated parking if staying somewhere larger.

Nemo, if you stay in Arezzo, the higher area of the town around Piazza Grande is very atmospheric. I stayed in a B&B there. There’s accessible parking available just beyond that area to avoid driving through ZTL zones. Here’s an excerpt from my trip report:

“I stayed at small De’ Montetini B&B, and the location was perfect. I enjoyed taking many photos in the medieval portion of Arezzo, loved the jousting event & entire day’s activities leading up to it, and the food in this city was wonderful. My B&B host wrote down a few recommendations for me, such as Antica Osteria dell ‘Agania, and they were all good. (I couldn’t believe how many locals kept coming into Antica Osteria dell ‘Agania the night I was there!) There’s also an antique fair each 1st Sunday of the month, so both activities were happening that day. Arezzo is also a good uphill workout to be ready for Montepulciano!”

I see Valadelphia & I were thinking alike. Yes, be sure to fully understand the ZTL restrictions. There’s lots of posts here of people who received very expensive tickets.

We also are going to Tuscany mid May and originally I had booked the car rental from FCO, but from the advice where we are staying in Pienza, they recommended taking the Leonardo train from FCO to Roma Termini and then taking a train to Terontola- Cortona and renting the car there. Just a short drive to Pienza from there. This way we don’t have to deal with all of the traffic around Rome and the highways.
Then return the car there and use the train to wherever you need to visit after Tuscany.
Less anxiety!!

Agree with the opinion on the bigger cities/towns with the ZTL and parking considerations.

Is Arezzo will be a better option for us, like you suggesting? Good place for atmosphere and parking ok-ish? So you all think to leave San Gimignano for a day trip rather then a base, right?

So we should we stay in Arezzo first, then Montepulciano next, then Rome. Where we should then be picking up car?

Pammy - What is your general itinerary, can you share? Great point on Pienza car rental.

Chiusi would be closer to Pienza than Terentola-Cortona and I am pretty sure more car rental options there

So Arezzo is a better base than San Gimignano - general consent?

It depends on where you want to visit/ day trip/ road trip
Arezzo is to the east, SG to the northwest
You really have to spend some time with a guidebook and Google maps to determine where you will go from whichever base you pick.

It sounds like you are planning a nice family vacation! I would definitely suggest Arezzo over San Gimignano. Arezzo is a bit larger and a bit less touristy. I had friends visit San Gimignano last year and they said they had a horrible time because of the number of tourists. They had difficulties making dining reservations and had to leave the city for dinner.

Your 2nd choice for Montepulciano is actually my favorite hilltop town. I have been visiting for years and will return again this year. For places to stay, I would suggest Fonte Martino B&B, which is now my "go-to" place. It has a beautiful setting, great views, and incredible owners. My backup choice is Charming Homes Montepulciano, which is an apartment at the base of town. The owner is very nice and the apartment is comfortable.

For the train and rental car, I echo a previous post about taking the train to Chiusi. Very near the train station is an Avis/Budget rental agency. Just be sure to check their hours because they can be limited, especially on weekends. As a side note, I have flown into Rome many times and rented a car there, which has been the easiest in my experience. The drive to Tuscany is about 2 hours (more the further north you go), and really isn't that bad. Do what you feel is safest, though!

Have a wonderful time! -Norman

Booked Arezzo in lieu of San Gimignano. But just realized that it maybe too close to Montepulciano (our first base). Is there anything in between Lucca and Florence/Prato that would be a better base so we can cover that area?

I prefer Siena over Arezzo.

The recommendations were to avoid Sienna as a base with the car. What was your experience?

Arezzo is much bigger than Siena, and neither are good bases to drive in and out of. I always pick up a car at the airport (can't speak to anyone else's problems with driving after a long flight). I'd stick with Montepulciano, and if Florence is a must then consider Barberino, Greve and Panzano for your second stay - close enough to San Gimignano (with Certaldo) by car, and you can catch a bus into Florence.

I have a link somewhere about parking safely and practically on the outskirts of Florence. I'll keep looking.

"The recommendations were to avoid Sienna as a base with the car. "
Our experience was just the opposite during a 3 week driving vacation around Tuscany and Umbria a few years ago. We found Siena to be an ideal central location for explorations thru the nearby countryside.

My understanding is you won’t have the problems with ZTL zone laws if renting a car in Siena. I did this once and even though you cannot keep a car in the center, you can park it outside.
Another thing I liked about Siena is the ambience at night. I especially enjoyed sitting on the ground sipping a lemoncello in Il Campo Square.
Furthermore, the drive from Siena to Montalcino is especially scenic with its hilly windy roads featuring many different landscapes with postcard views. Pienza’s old town is worth a stop too. From there you can continue on to Montepulciano which is another enjoyable driving experience like no other as you maneuver into the town center.
I liked San Gimignano and the drive to get up to it. From there I drove to Volterra and that drive also offers incredible views of Tuscany that was very different from the rest of the Tuscan countryside fearturing lots of trees, it was very green.