Suggestions for a Tuscan base

Hi Flori, Florence, Siena, Pienza, Montalcino, Pisa, Lucca, Volterra and San Gimignano are places where walking won’t be a problem. However, I don’t recommend Montepulciano though because it's hilly.

If you’ll have a car Pienza
If no car Lucca

We found Siena to be rather steep and Montepulciano was a killer, beautiful but tough on the knees for sure

With a month, I suggest having two bases, one more to the north, the other to the south. Otherwise, you’ll be doing a lot of driving. Many of the towns were built on top of hills for security, but are fairly flat once you get up there.

I agree with the suggestion of at least two sites. You will be well served to have a car in Tuscany. Any of the towns mentioned will work; all are steep, some more so than others. None are huge so walking should not be a problem.

I would look for towns near the more popular tourist destinations. We have stayed in some of the cities mentioned, but also stayed in “no name” villages with equally attractive accommodation and sites.

Enjoy your trip, no matter what location you stay you will have a great time.

Somewhere in or near Siena would be my suggestion. It's central to all of the pretty little hill towns to the south as well as being convenient to the Chianti region immediately to the north. Parking in the underground lot at the train station costs 2 Euros per day, it's right on the SR2 for getting in and out of town, and is well away from the dreaded ZTL's that cause people so much angst.
From parking there's a series of escalators that will take you up into the town itself or, failing that, it's about a 10 Euro taxi ride from there up to the Campo.
Once up in the city proper the walking is relatively level - maybe some undulating grades but nothing that caused these old legs any distress during a visit back in '19.
Might add that there are several car rental agencies just a short distance from the train station, making the pick up and drop off pretty easy.
You'll want to review other RS threads for discussions about driving in Italy and generally do your homework before getting behind the wheel and setting off on your driving adventure. Penalties and fines for the unwary can be quite punishing if you're not familiar with the local driving rules.

If you are hesitant to drive (as am I), Florence is an excellent base with fantastic rail connections. Of course, there are some hill towns with no train access but some like Grieve have bus service for a day trip or even an overnight or a longer bus ride like Siena. In any case, you could even get to the Ligurian coast for a day trip, overnight or weekend adventure without the hassle of multiple base camps. There are some lovely beach towns away from the more crowded areas (Cinque Terre) but easily accessed from places like Rapallo or Chiaveri or Santa Maria Liguria...many grreat choices. SO muh to enjoy in Florence as well with great bus system too....and quie cheap. A favorite for me and any quest that ever came to visit me was a bus up to Piazelle Michelangelo (which is too uphill for me) then the walk back down whch is lovely. Also Fiosole is only a 20 minute bus ride outside of Florence and is a perfect day trip to see some ruins and have a lovely lunch etc. No matter what you choose (so many options) it will be lovely....lots may depend on the month you go...super hot in Florence July/August which makes the beach even better! Have fun planning!

Lucca can also be a great place from which to rent a car for part of your stay. It appears that the Hertz office in Lucca that I rented from is still there, a very short walk from the town center. So, in addition to easy rail access to Florence and Pisa, you can rent a car to expand your sightseeing. We enjoyed the scenic drive in the hills to the tiny town of Vinci to visit the small Leonardo da Vinci museum and a ceramic workshop run by a man from Sicily.

Thank You All. Your replies have given my wife and I many options to consider. Thanks Again!