Heading to Island of Elba, Florence and Milan
To qualify this reply, we're not the type that has to eat four-star when in Italy. When we visit, we tend to not do ristorantes except for our last dinner before heading home. We generally split our meals between trattorias and osterias.
That said, we were just in Florence last week and thoroughly enjoyed Natalino. Wife had a pear-filled tortellini in gorgonzola sauce - flavors were muted, not sharp - excellent dish. I had vegetable ravioli with zucchini flowers and curry - again excellent use of melding flavorings, nothing overpowering (as curry in the US generally is). Our entree was the Florentine steak for two. They have incredible patati fritti as well. We kept the wine simple - a Nipozzano Chianti Riserva that was strill fruity and about 20Euro. Yes that sounds very American, but it really isn't.
We also ate at Mamma Gina near the Pontevecchio, but that nothing exceptional, so you can avoid it.
Keep in mind anything right around the Pontevecchio will probably be 20%-33% more expensive than eating 3-4 blocks away - and we believe the streets on either side of the Arno in the Pontevecchio area feature more "dumbed down tourist" dining based on our experience.
You might also want to look for a copy of a 2005 issue of Bon Apetit that featured Rome/Florence/Venice - lots of good info in that issue. We visited Le Volpi e l'Uva (Pza. di Rossi 1r) - tasted some different Tuscans and brought home six bottles of various local wines. Highly recommend them and/or I Fratellini. We tried Olio e Convivium to try some wines and olive oils but got a lot of attitude about coming in just before their afternoon break - not friendly at all.