If you want a genuine Firenze experience, this is it: Wonderfully charming apartment in the middle of Florence. Very old building in a side street to Santa Croce. Communicating with the concierge, Seniore Lamberti, adds to the special flair.
Although super-old, the place is very convenient and even has A/C (very helpful if you decide to visit end of August.
Guido is extremely responsive to any requests. Highly recommended!