Blue G. is a very good place, near the Piazza Maggiore, 3mins by bus. Big house, living room and kitchen. Like your home away from home. Little Blue (her dog) is also very quiet. If you don't want to stay in a loudy centre, this will be a place for you.
I came to Bologna during Cosmoprof so it's a little bit hard to find a taxi, but nevermind, there is a Blue Car service.
Simona is also a kind host who is willing to support you.