I can't recommend Sante's "Residenza San Vitale" enough. I stayed here for a month and enjoyed the apartment and it's location.
It's very close to grocery stores, a small market shop/stand next door (super convenient!), close to parks, bike & pedestrian paths, in a quiet neighborhood, a 20 min walk into the city center and also a block away from bus lines that will bring you straight into the city center. The apartment itself is wonderful, and has everything you'd need for short or long-term stays. The large terrace/deck outside was a treat. My dog & I enjoyed soaking up the sun there in the mornings. I hope to return to Bologna, and when I do I will try to stay here again! Thank you Sante for your hospitality.