For your stay in Florence, I actually recommend Tiziana's place. It's just in front of Porta di Prato Station and only 10 minutes walking from Santa Maria Novella Train Station; if you prefer, you can easily reach the city center by bus or tram: the stops are very close to the apartment. At the end of the day, it will be a pleausure to have some rest in a cozy and extremely clean room!
I was travelling alone to go to a concert (10 minutes walking from the stadium! you definitely have to consider this place if you're going to an event over there!); my communication with the Host was clear and precise and I've been offered good tips and advices to plan my trip in every detail. I've had breakfast too, and stayed in great company with my Hosts. I couldn't ask anything better! :)