Florence is best in the off-season; the summer months are painfully crowded. If you love art history, this is your chance to dive deep. Tuscany contains a mind boggling number of sights and experiences. The hill towns, like San Gimignano, are incredibly atmospheric (and touristy). Sienna's duomo is a stunning architectural creation literally cantilevered out over a hill. Get out of town to see the vineyards. Arezzo's stunning Piero Della Francesca murals are worth the trip alone.