Movie Better Than the Book?

At dinner last night, the less short of the short people claimed that while the Percy Jackson movie was significantly worse than the book, Cloudy With a Chance of Meatballs was, in fact, better. The explanation, I hold, is that one is a children's book while the other aimed at pre-teens. the Percy Jackson books have much more room to develop characters and plot intricacies that do not translate well to the hour and a half film format. The former, on the other hand, needs to be filled out to be made into a movie and thus becomes more interesting.

I'm wondering if anyone thinks there are exceptions to this, movies made from books other than those geared towards young children where the film was better than the original fiction piece.