The Hostel Archi Rossi is a great place for artistic souls to stay in. The walls are decorated with a funky and rather impressive mural. If you ask the friendly staff nicely, there's a chance you can add some flair of your own, given that you can find the space for it. The mural and a plaster version of Michelangelo's David set a fun, gaudy sort of scene for an entertaining and very Florentine place to stay.
Rooms are remarkably clean for a hostel which deserves mention in itself, with super high ceilings and (sadly) art-free white walls. But, the cute wrought iron bunk beds and pressed wood furniture with individual, locking cabinets make the place feel cool, sleek and modern. Bathrooms are tidy and functional (which is all you could really ask of a bathroom). If you're tired, then stretch out on nice, soft bedding, or relax in the interior statue garden or the bright second-floor terrace.