This was my base when exploring the Tuscany countryside. Pienza seems to be in the middle of it and San Gregorio is very well located just outside the city walls of Pienza. The hotel is beautiful, it has nice rooms, very spacious atmosphere, friendly staff and good breakfast is included in the price. There is free parking in the basement, it is a bit tricky and you need to be careful with all the pillars there but there is plenty of space for cars.
The only thing that was annoying me was the sound of the pigeons. But this is of course not the property's fault. I had my window open during the night and when they started 'singing' they did not stop. I should have closed the window but I was too tired to get up. On the other hand, if you like pigeons there are plenty of those :)