My three favorite restaurants in Florence are:
Osteria Caffe Italiano
via della Condatta, 12
055/289020
Frankly, this is one of my favorite restaurants off all time, anywhere. Get a reservation.
Quattro Leone
Piazza della Passera, Via dei Vellutini 1/r, near Palazzo Pitti, Florence, Italy
055/218562
Hard to find (on Pitti Palace side of the river), but worth it. Get a reservation.
Acqua Al Due
Via Dell'Acqua
055/284170
Serves assortments of their dishes. Like 3 different salads, pastas, desserts, etc. so you get to try a bunch of stuff.
My two other favorite places, I can't remember the name of but I know how to get to ....
A wine bar serving excellent snacks with outdoor seating, right across from the main entrance to the Pitti palace.
A lunch place near the Mercato Centrale (another do not miss place -- buy some dry mushrooms and other stuff there) where only Italian is spoken and only 2 or 3 things are offered. Will try to find the names.
If you want to spend $$$, I have been to
Beccofino and
Cibreo, which are both excellent.