Florence is my favorite city in the world. My one suggestion is to get up really early there and hit the main area around the Duomo, Palazzo Vecchio, etc. You can get some great shots without any crowds there. Have fun! Looking forward to seeing your pics.
The 70-200 f/4 would have been great to have when I visited (105mm was my longest). Mark my words though: you're going to LOVE the 16-35 f/4. Most used lens, by far.
