I was looking at buses to and from Florence. It looks like Lucca is around an hour and a half drive and Siena it's a little under an hour and a half. They also have buses going from Siena to Rome but that is about a three hour drive and close to 20 euro (eeiik!) I will do some more research on both cities and get back to you soon on what I think. Right now it all sounds great. All we are lacking is time. We may have to pare our options down so to fit our schedule but lets do the research and then decide.
Would it make sense to spend a night in Sienna on our way to Florence?? It is on the way. Just a thought.
Lets throw out Pisa. Another time maybe.