bagold: Depends on your preferred style of travel. If you enjoy seeing a packing a lot of interesting sights into a trip, especially in a place that you might never get back to, you could squeeze a side trip in. If, on the other hand, you like to get a feel for a place, 2 days are barely enough for Florence, one of the great art cities of the world.

I've been to Florence twice for 5 days, both times with intentions of side trips to places like Siena and San Gimignano. I loved Florence so much that I couldn't bring myself to leave, not even for a little trip to Fiesole, either time.

I agree with all the suggestions above. There are so many great things to see and do in Florence, especially if you're interested in art and architecture. One thing that no one's mentioned that's one of my favorites is taking up a walk up the hill to Piazzale Michelangelo, which overlooks Florence. The walk itself is lovely, but the view is phenomenal, one which I'll never forget. You get a feel for the scale and greatness of the Duomo that's hard to get when you're standing closer to it.

Both of my trips to Florence were quite a while ago, though, and another issue may factor into your decision to stick around. I've been told by lots of people who've been to Florence in the last 10 years that it's become inundated with motorbikes, to the point of it being difficult to walk and not as enjoyable as in the past. That wasn't my experience, but it's been 12 or 13 years since my last time there. Anyone care to comment on this?