In Bologna you'll want to look at the Grand Hotel Baglioni. Even though it could use a renovation, there isn't anything else in Bologna that comes close to it. The location is ideal as well.
As an alternative to Grand Hotel Baglioni, which I wholeheartedly agree is by far the best in Bologna, consider the boutique Art Hotels which offer more of an intimate feeling.
Sorry, but I'm pretty sure there aren't any luxury hotels in Ravenna.