All I can tell you is that Tuscany is road bike heaven. Mostly quiet roads and very hilly. We went with a group from Co-Motion cycles,
http://www.co-motion.com/ who built our tandem, and rode with Andy Hampsten and his company Cinghiale Cycle Tours. Check out his site at
http://www.cinghiale.com/ We did out and back rides from 2 central locations in Castagneto Carducci, near Pisa, and A small agrotourismo near Trequanda. Then two big transfer days. Rides to Pienza, Montepulciano, etc, Beautiful and mostly very light traffic. Give either of them a call or visit and they will gladly help you out. It's really great to bring your own bike as well, as trying to find a tandem that fits would be impossible there. Good Luck!!