There will be a lot of people expecting The Hobbit to be pretty good. (I'm expecting to like it for eye candy myself).

As an X-Fan, the X-Men First Class trailers look really good, bringing in elements and characters from the comics missing from the other films. The X-Men movies were different compared to the other recent comic movies because it didn't do "origins". The team was well established by the time they came to rescue Rogue and Logan. Other new students (like Colossus, Siryn) were just there in school as the movies continued. It was kind of appropriate since the Mutant X-gene was Stan Lee's way of getting out of coming up with origins for new characters. So I think there's room to tell a story of the X-Men origin in the movie continuity.

As for good prequels: Casino Royale and Quantum of Solace were pretty good.