Coroleu House is the homiest place I have ever stayed in- literally. It's a house, and the misadventures I had in telling Jose Maria when I'd be arriving and then being super late were hilarious. (Sorry about that once again) Just make sure to tell him when you'll be arriving as there is no reception! The place is beautiful, has a lovely backyard garden, a computer you can use, is spotless, and the kitchen is pretty great. (Drip coffee was a nice touch of home for a North American.) Recommend!
Maison is in a great location (if you don't mind trekking up four flights of stairs to get to it) just up the street from the Duomo, and has a nice little kitchen/common area where you can cook to your heart's delight and make friends. There are two bathrooms that are quite clean and two dorm rooms with cool ceilings, as well as perfectly comfy beds each with a different blanket and character. Yuri, the owner, is a mite gruff yet very nice and accomodating. If you care, the wifi is awful.
The fact that it's in an old monastery is very cool- the bell still hangs above the entrance to the kitchen. The fact that it has a 2am curfew is a bit stringent, if you're in Florence for the art as well as the nightlife, and the lockout of your room from 10am to 2pm also sucks a bit. Don't be discouraged though- it has a pretty good kitchen, free computers, and a large common room/dining hall where you can make friends. The staff are kind and helpful, and the place is very clean and secure.
Nice place, quite well-situated as it's next to Westbahnhof station and so metro travel into the city centre is made easy. You could also walk along Mariahilfer Str. and do some shopping if that's your thing. Staff are very friendly and helpful, rooms are clean and you must use your card two times to get to your room, and again to access your locker. Thumbs up for security! The bar has quite a cool atmosphere and friendly bartenders, as well as a 1 euro-activated pool table.
Great place, very clean and well-situated. Too big for my taste though, and didn't have a super cozy atmosphere.