Montepulciano , Montalcino, Piensa? One overnight stop

Where are you coming from?
Which other hilltowns will you have seen?
Assume you will have a car?

Any of the 3 would be fine -we like Pienza for the easy access/parking with a car

My wife and I stayed just outside Monticchiello last October. It was easy to get around by car from there. Montepulciano and Montalcino are hill towns with difficult access for vehicles but parking outside (and below) the town centre. Pienza is easier to get into with a car. If you want to park at or close to your accommodation, Pienza or a smaller town would be better. Montepulciano was my favourite to visit among those three.

Agree Pienza is a good choice. Easy to get around, and not as strenuous walking as Montepulciano with it's steep grades. We enjoyed Pienza the most, and loved all the Pecorino shops. Had the best ever Cacio e Pepe in Pienza.