Montepulciano is a wonderful hill town that is both accessible and easy to navigate. The views are amazing, so the drive is worth it. (I do not recommend trains for getting to all the small towns.) Don't miss the leather and copper artisans likeBottega del Rame. There are many specialty shops for every taste.
Chianciano is another great small hill town complete with thermal spa and olive trees. Stay in an aguriturismo for an authentic and memorable experience.
There are so many places to see in Italy. Go, eat and sleep there soon!