Just returned from a few weeks in Tuscany.
Please do not miss the interior of the Duomo in Siena...unbelievable.

For wine purchases, we were so impressed with the Enoteca Italiana in Siena's fort, the only government-run enoteca in Italy. Great information and English speaking assistance. Ask for Tina, she's fantastic. This is the place to go to learn, buy, ship, and fuggedaboutit.

One of my favorite afternoons was spent renting bikes ($5 for 2 hrs.?) and riding along the tops of the walls in Lucca, a fascinating town near Pisa. Gorgeous.

Two of our favorite meals: Le Terrasse at Hotel Cisterna in San Gimignano, a town not to be missed in its own right (including the amazing Museum of Medieval Torture).
Also, Il Castello in Alto Certaldo...the old town above the more modern burg. Great homecooking that is extremely affordable. Hometown of Boccaccio (of Decameron fame).