I found that many of the agriturismo properties required a week long stay if traveling there during high season (summer). But there are many lovely options. We stayed in L'Orta di Panza, (roughly translated as "Grandfathers Vegetable Garden" :)) and it was absolutely perfect! It was in Montepulciano - just outside the town center. We had lovely views over a vineyard and an olive grove, a beautiful pool, a delicious breakfast each day, and, best of all, the most delightful service from the wonderful family that owns it. We staying for three nights and used it as a home base for exploring the hill towns. We rented a car in Rome (Termini) and drove there - it was very easy and very relaxing. We had a two bedroom apartment (family of four) with a kitchen. We ate a nice lunch out each day in a different hill town and then ate a light supper at "home" each night after a swim in the pool and enjoyed a bottle of wine we picked up in our daily travels.
Montepulciano is not in Chianti region but is in the heart of some of the most fabulous wine territory on earth. It was like heaven!