I'll second Starlight Express, Mamma Mia, and The Addams Family. I guess I have to add Cats, because according to a lot of theatre purists, you aren't supposed to like that either (and I love it!).
Have to agree with original poster, "Rock of Ages". I just grinned through the whole thing recently here in Chicago, which was skewered by Chicago reviewers for not "being Equity". But both the cast and the audience had a grand time.
Not to be confused with "We will Rock You" that I saw in London with 3 18 year olds, who thought it was the greatest piece of theater ever conceived.