We only spent a night at Nicola's place and it was extremely nice. The appartment is a bit away from the city center but very well connected by bus. And walking or biking to the center is - in fact - very pleasant, crossing districts away from the main touristic places.
Nicola is a wonderful host. Since we already came before to Florence, we went together to Fiesole. We also enjoyed Nicola's deep knowledge of the city, from yummy ice creams to small stories all around Florence!