We had a great stay at Marc's place. The location is pretty much perfect. Right at the edge of the center, but still (barely) outside of the dreaded ZTL. I was so worried about getting fined in the ZTL we left our car at the Park + Tram but there was no need after all, Marc provides instructions on how to drive and you can park in a private courtyard. The entrance to the apartment is also inside that courtyard making it reasonably quiet. I say reasonable as there was still some noise, but at night it was fine! There was a thunderstorm the evening we arrived, and we stupidly opened the window to let in the fresh air... and a dozen of mosquitos :( This is probably a known problem as the apartment did have plenty of mosquito repellants available, which we gratefully used the next evening (as well as the aircon, windows closed!!)
During our 3 day stay we always walked into the center for the sights (15 mins or so), and on the way there you pass plenty of restaurants - we had dinner close to the apartment every night actually. The little supermarket around the corner was also very convenient. I'd recommend this place to anyone staying in Firenze.