I agree with everyone about Montalcino and Il Giglio. My husband and I stayed there last April, we loved the room upstairs with the patio and view.
Grappolo Blu was our favorite restaurant. They have a heavenly bean soup. We made day trips to Pienza, Sienna and Montalpulciano. We also toured the abbey at San Antimo and had plenty of downtime in the enotecas in Montalcino.
We stayed there five days, then made the drive North to Venice for three nights. I thought it was perfect. Venice is very different from Tuscany and a nice change.

Buglady, if you haven't done so, go to the SlowTravel website for lots of good info on all these towns. Although many recommended southern Tuscany to us, others pointed out that since we wanted to spend time in Florence, Siena, and San Gimignano, we might be better off in a more central area. We will be staying near Castellina and Radda. Found a place here, and these people are incredibly helpful: www.totuscany.com