Car rental in Tuscany

I don’t know if your plan are set in stone, but, in your shoes, I would do it this way:
ROME (visit Rome without car)
train to
FLORENCE (visit Florence without a car for a few days)
rent car in Florence drive back south to Tuscan countryside locations
TUSCANY (visit Tuscany with car)
continue to Puglia with the rental car (a car is useful to have for Puglia)
PUGLIA (visit Puglia towns with the car)
return car in Bari, to be visited without car
BARI (visit Bari without the car)
train to Rome (I’m assuming you fly back from Rome)

If the above doesn’t work for you, due to your plan already being set, you can rent anywhere in Rome. If you are in Rome for a few days, I would rent from a city location (always cheaper than renting at airport). If you are driving to Tuscany upon landing then it makes sense to pick up at the airport.

You can return the car at the Santa Maria Novella station in Florence. All rental companies are at or near the station. I have given directions in past posts recently. Use the search box above.

I'd take Roberto's advice.

If you share your exact itinerary we can fine tune advice.
Are you spending time in Rome and/or Florence?
Where in Tuscany will you stay?

When you Search the forum be sure to filter by Type and Date.
There are dozens of recent posts about pick up/drop off rental cars.

Here are some:
https://search.ricksteves.com/?button=&date_range=2y&filter=Travel+Forum&query=Florence+rental+car&utf8=✓

Make sure all drivers have an IDP and do your homework on driving in Italy.
We always use AutoEurope.com

Thank you for your comments. We are not staying in Rome this time, arrive late in day from Canada and considering just heading to bed at airport hotel. Up next morning to rent car and head to Tuscany. We are meeting our son and family in Florence where we will give up our car and are considering training to Bari where we will rent again vehicle for the 5 of us.

Does that sound reasonable?

Thanks for your help

Sounds reasonable
Just alter Roberto’s plan a bit if you don’t want to drive Florence to Bari.

How many nights is this trip?

Arrive Rome- 1 night airport hotel
Get car
Drive to Tuscany- where will you stay?
Drop car in Florence- how many nights?
Train to Bari
Rent car as needed

Make sure vehicle is large enough for 5 plus luggage

Train back to Rome?
Where are you flying home from?

Our trip is 25 nights.
One night in Rome
7 nights in Tuscany. We would like to stay at 2 places. One in or near Montepulciano and one in or near just north of Poggibonsi. Thus in not booked so welcome suggestions
Train to Florence for one night ( have been before) travel to puglia for two weeks. One week in Vieste and one week near Ostuni in hills. This is booked. Will do day trips We will have a one year old with us in puglia.
Train to Rome to fly home.

Welcome suggestions on Tuscany bases and Rome hotel near train station. We are not big city people and like countryside and rural stays
Thank you

One night in Rome
Is this the night of arrival, or the night before your return flight? It would appear that you intend to head to Tuscany right after landing (on the same day or the day after). If so rent the car at the airport and don't bother to go downtown (you must have been to Rome before). If you plan to drive upon landing, after an overnight flight, take it easy, as you will likely be tired and jet lagged, therefore not in the ideal conditions to drive.

7 nights in Tuscany. We would like to stay at 2 places. One in or near Montepulciano and one in or near just north of Poggibonsi. Thus in not booked so welcome suggestions.
There are plenty of accommodations in both areas, but I don't have much experience on accommodations in the area since I generally go from Florence or my country house. My only suggestion is not to stay in Poggibonsi proper. It's kind of a large not too pretty industrial town which is more modern than most due to being destroyed during the war. However there are plenty of accommodations in farmhouses and country villa hotels nearby, like in or near Barberino, Colle Val D'Elsa, San Gimignano, Monteriggioni, etc.

Train to Florence for one night ( have been before)
Train from where? Poggibonsi? and what do you do with your car? If you plan to visit Florence, just drive there for a day from your accommodations in the Val D'Elsa area (Elsa Valley, where Poggibonsi and all the aforementioned towns are). If you don't need to see Florence, then don't bother. Enjoy the countryside then drive to Puglia when you are done.

travel to Puglia for two weeks. One week in Vieste and one week near Ostuni in hills. This is booked. Will do day trips We will have a one year old with us in Puglia.
You need a car in Puglia for what you intend to do, especially with a 1 year old. Neither Ostuni, and especially Vieste, are easily reachable by public transportation. Also a car would allow you to take day trips easily. I would also consider a 3rd base for Puglia (the region is huge and it takes 6 hour drive from Vieste to the extreme point to the South at Santa Maria di Leuca). Alberobello, Locorotondo, Castellana Grottoes, Martina Franca, Ostuni are all popular destinations, and are all close to one another, so they can be visited from one base. Matera is also doable from that area since it's only about 75 min drive. Ostuni is however the farthest down of the bunch, so less ideal as a hub for all, but not too far either. But that is already booked. Another location you could consider is Otranto. If you go in summer, the beaches of Salento are great.

Train to Rome to fly home.
I presume you are going to Rome the night before the flight. I would stay at the airport, unless you care to spend the evening in Rome. If you decide to stay at the airport, I usually stay at the Hilton Airport, across the Terminals. If you prefer to stay near the station I've stayed at the Hotel San Remo last time I was there in the area (several years ago), but there are many on Via del Viminale area, just near the Opera House. That area is pretty safe. If in the end you decide you don't want to bother with the train, and instead drive the 5 hours from Puglia to Rome, then I definitely suggest you drive to the FCO airport, and stay at the Hilton after returning the car.

Another option I would consider is:
Land at FCO
Immediately head to Florence by train (likely change at Roma Termini or Roma Tiburtina station)
Stay at least one night in Florence to rest before renting a car.
Pick up car in Florence drive to Val D'Elsa (Elsa Valley area). Stay there a few days.
Drive further south to Montepulciano/Pienza area. Stay there a few days.
Long drive from Montepulciano to Vieste (7 hours on a good day). Stay there a few days. Visit Peschici and Vico del Gargano while in the Gargano peninsula. The Gargano is not easy to reach or drive out of. So not ideal for day trips afar. Roads are very narrow and curvy, so it takes forever to drive anywhere from there.
Drive the 4 hours from Vieste to Ostuni. Stay there a few days. Visit the towns I mentioned above.
Possibly stay in Otranto a couple of days (not sure if you have the time or if it is possible given your existing reservations)

Go back to Rome by car or train (if by car return it at the airport and stay at the airport)

Thank you so much. I will look into this on the weekend. Can you tell me re trains if I reserve in line for a regional train it says you must validate your ticket. What does this mean and how do you do it?

Long distance high speed trains (like Roma Termini to Firenze SMN, or Bari Centrale to Roma Termini) don’t require validation. Tickets for those trains are like airplane tickets. When you buy them they come with a reserved seat. You can purchase them online at a discount, but if you plan to take them upon landing it’s risky, because if your plane is canceled or bigly delayed, they are not refundable. If your plan is to go to Florence as soon as you land you should buy the ticket when you are at the airport station. You’ll pay full price, but no risk. If you know the exact date and time you want to travel by train from Bari to Rome, you can purchase ahead in the website below (two companies to choose from)
www.trenitalia.com
www.italotreno.it
The only trains which require validation is regional (commuter) trains if you buy a paper ticket at the station. If your plane is use the Trenitalia app or purchase on line there is no need. Paper tickets are validated by inserting them in the validating machine to date stamp them before you board. The ticket is valid for 4 hours after that. The only time you will get on a regional train is from the airport to the Roma Termini, Rome’s main station, to catch the train to Florence, or on the return portion from Rome to the airport. See the tutorial below on how to validate a paper ticket for a regional train.
https://youtu.be/sxJBtMdJf30?si=cMeD2puqbhNM6h0D

There is no reason to reserve a regional train online. There are no discounts on regional trains, they are like subways. Just buy them at the station at a ticket office or automatic kiosk. Remember to validate before boarding. You can also buy tickets on the Trenitalia app.

The reason why they require to validate paper tickets on regional trains is because those trains are like buses or subways, no specific train or seat reserved, otherwise you could use the same tickets multiple times. By requiring to date stamp them, you must use those paper tickets within 4 hours.
If your plane is buy tickets on regional i via app, I think now you must click on “check-in” on the app before boarding, and that is equivalent of validating the paper ticket. I’m not sure about that because I haven t used the app yet. Someone else will chime in.

As always, Roberto's advice is incredibly detailed and well thought out and based on real experience.
I also think you'd be much better off taking the train from Rome to Florence on your arrival day, (buying tickets when you get to the airport). It will be a long day, but you won't be driving, and it's so much less stressful sitting on a train and watching the countryside go by than trying to navigate driving after a long flight.

In another post Roberto has given very detailed instructions on how to drive out of Florence city center avoiding the ZTL, if you rent the car at the train station. I haven't done this 'live' yet, but using his directions and google maps street view will give you a good sense of the streets and turns.

Thank you so much for all your advice and the information on validating tickets. That little you tube video was great.

If you’re still looking for a place to stay in Tuscany, we stayed here several days.
https://www.tenutasantilario.it/en/home-english/

A little off the beaten path, lovely , great walking, close to sites
And ended up returning the car in Florence which was stressante but if I can do it I bet you can.
Enjoy!

Thank you for the hotel recommendation and driving encouragement. The hotel looks lovely, we are still attempting to natrow down to two bases and this is on our list now. Thanks!