Perfect town in Tuscany?

Try Siena. Your requirement of a house rental may be the challenge. Many of the villages are very hilly as u might expect. But Siena is easy to get around with a lot to, see and do. Transport options also are easy
From Siena. Pienza might be another option for u .

Walking distance to a town is tough, but Montalcino comes to mind as well as Pienza and Lucca.

Some travelers home base in Sienna and do day trips, to places of interest, from Sienna by rental car.

We loved Montepulciano but stayed in town and glad we did. It is very steep and a bit of a pain to get in and out of. I would go back, but not sure it's the best place for walkability.

We visited Pienza day tripping from Montepulciano and really liked it. It's a charming flat hill town, easy to access. The surrounding area is lovely. It felt like a place we could live. When we go back to Tuscany we will likely stay in or near Pienza.
Lots of towns and things to see/do close by- San Quirico, Bagno Vignoni, Montalcino, Montepulciano, Siena, Abbazi Monte Oliveto, more I can't even remember all! Orvieto and Bagnoreggio are reachable as a day trip from Pienza.
Not great for transportation -no train.

Siena is bigger and busier- lots to do but can be done as a day trip. And you should visit. Not sure walking in/out of town would be easy there.
Have not been to Montecatini or Lucca.

Prioritize a list of what other towns you want to visit in Tuscany and pick the base that serves that purpose. Assuming you will have a car or 2?
If not then you'll want a town with good train/bus service.

In your case I would rent an Agriturismo (car rental necessary).
Finding one within walking distance from any town may be a challenge but there are some. Use a search engine and then check location on Google Maps.

I could not imagine a more perfect place than this...

http://casamoricciani.com/en/the-villa.htm

Great location and amazing hosts. You will not regret it at all.

Montepulciano is very steep, but when you visit it, take the small orange shuttle bus up to the top of town. It’s about 1.20 Euro - a bargain!

There’s also a tourist bus from Montepulciano that visits nearby small towns - separate from the local bus that goes to Pienza, for instance. This is in case some of your group wants to sightsee separate from a car.

Pienza would probably be a great base for you in Tuscany.

Castellina in Chianti is very nice and easy distance from Florence & Sienna.

We rented a villa in walking distance to Panzano in Chianti. We love the villages in Chianti.

Another vote for Pienza. It’s beyond charming and easily walkable. Have stayed in Siena twice, really dislike it.

We love Siena!

We also really like Siena and returned to stay more days than the first trip where we were there just two days.

Hi Julie,
Maybe check out Pitigliano?
Tante belle cose.
I am done. The end.

You might want to search Airbnb in the area of either Pienza, Monticheillo, Montepuliciano. I found a lovely 6 bedroom villa in Monticheillo. When splitting the cost 8 ways it makes much more sense. Montepuliciano is one of my favorite hillside towns but its steep like the others have mentioned. I will be there with my parents in May and plan to use the bus to take them to the top and leisurely work our way down. My dad is 82 and doesn't like to walk. Pienza is a flat quaint town and easy to get around. They have a Coop grocery store on the outskirts of town for any necessities you might need. Montepuliciano has a wonderful farmers market/flea market on Thursday mornings. Have a great trip!

We spent the first week of July driving through Tuscany. We spent three nights in Volterra, from which we visited San Gimignano, and then three nights in Montepulciano, from which we visited Pienza and Cortona. We also stopped for lunch in San Quirico on our way to Montepulciano.

We enjoyed each town, but really loved Volterra.