Tuscany in Mid May : Family vacation

Thank you for all the Fodorites information. We are now thinking : fly to Venice from LA for 3 nights. We do want to stay in Florence for maybe 3 -4 nights. We would like to stay in a smaller town, as well too, to have some of that experience, but not too small, also for a slower pace and smaller size experience. Would you suggest Ferrara?? Pieza seemed too small to me from what I read. We would like to go to Siena and Lucca also. I would love to go to Chianti and Montepulciano. My husband does fine sitting in a car but no walking uphills or distances right now. We are all fine with my daughter and I going off at times, occasionally, as long as my husband has a nice place to hang out, he is happy.
Is Cortona possible? Should we plan to rent a car?? It seems like the best way to get to some smaller town experiences too.
OK, now the latest tsomewhat crazy? thought, from my husband and daughter, is to fly from Pisa to Barcelona for the last 3 nights and fly home from there. We have 13 days, I think.
I really do need to make flight arrangements soon!
Thank you so much for any suggestions and thoughts!!