I staid at Guidetta's place as part of a group of eight people (two families). We have all been happy to stay here, adults and kids alike. Guidetta has been very easy to get in touch with and very flexible with our requests. All rooms were fully equipped, air conditioning was super and outdoor facilities were great (we used the swimming pool area and the BBQ). The house is nicely decorated and ideally located to get sun most of the day, with an orientation that makes it easy to enjoy wonderful sunrises. Location is good too. Pian de' Giullari is right by the Piazzale Michelangelo and 15 minutes away from Florence city center.
I would definitely recommend Guidetta's place to othr guests.