I highly recommended Walter's apartment in Florence. Walter is the ideal host. He's flexible to work with, communicates well and is very responsive. He's also highly knowledgeable about Florence, both past and present, and made great recommendations on sights to see, where to eat and nightlife. He's an all around good person to know.
The apartment was very cool. It's an old nunnery building with lots of character. The Internet works but is slow, but there is free public wifi in santo spirito the main square one block away. Santo spirito is an awesome neighborhood to reside, close to all the sights, but just off the beaten track to feel more authentic.
Overall, if you want an awesome host, cozy place in a cool neighborhood and within walking distance to everything, then this is the place for you.