Pienza, Montalcino or Montepulianco

I'm not much help because I think you would love them all. I suspect Montalcino or Montepuliciano would have more options for dinner, but you only need one dinner so it doesn't matter. I'll delete this post if others have more helpful advice.

The other thing to take into account is the passagiata in each town. We're splitting hairs here....

You might as well ask me which of my children is my favorite!

Can you drive into any of these towns without hotel reservations and get an affordable room?

You do not drive into the center of these towns, er, well, except by accident but that's another thread.

I would never try it. First, You just can't drive from business to business like you can in the US. Second, hotels don't look like they do in the US. You can't tell a building is a hotel just by looking at it. You will need to walk by and look for modest signs near the door. Even then you could miss it. Do you really want to hoof it around town looking for lodging?

Personally, I don't like to waste my limited sightseeing time looking for lodging. In addition, you will pay a bit more for less desirable accomodations than if you do your research ahead of time. But, there are others on this board who choose to travel that way. Maybe they can advise. In general, they are single people, they're staying at hostels. If you're traveling at high season that works against you also. If nothing else use the phone and call a few days ahead of time to secure accomodations and get directions & parking instructions. Depending on your accomodations, you may need to park on the outside of town.

Montepulciano will be your best bet for an overnight stay. Pienza possibly as well. Montalcino though is small, but it is still possible.

You will be happy with all of them. Definately do not miss the Abbiza de Sant Antimo just outside Montalcino.

Pienza has a car park that would be hard to miss--very easy walk into the center. Lovely little town.

Been to all 3 but probably enjoyed Pienza and Montepulciano the most. Stayed at an agriturismo a few km. outside of Montepulciano for a week and did daytrips around the region. As a previous poster stated Pienza has a convenient car park. It is very small but very cute! Have a great trip!