When in Florence, try and eat at Zaza's in the San Lorenzo district. It was listed in several guide books, and I was afraid it might be made out to be more than what was written, but I was absolutely wrong! The restaurant was fantastic... the veal chops were the best I've ever had. Good enough to make a trip back the next day for lunch to eat them again! Zaza's has an outdoor eating area on the plaza, and it's fun to sit there and leisurely eat lunch with all the locals enjoying their 2 hour repast!
It was busy and this was during November/midweek, so I cannot image what it would be like during the crowded summer season.