I generally never go see movies in 3D. There are some movies that are worth going to see, though. I went to see Avatar in (real) IMAX 3D, and to me, it was worth every penny. The movie was made to be experienced like that. It looked amazing that way. I also enjoy it when it is done to be ridiculous. I saw Piranha 3D, and it was fun and stupid. So for me, it has to be beautiful like Avatar or ridiculous like Piranha. No in between.
As far as older movies, I would like to see some in 3D, if the effort actually goes into making it look good. Going back to James Cameron, my wife's favorite movie is Titanic. We went to see it in 3D when it was rereleased. It looked great. I haven't seen any if the Disney 3D rereleases, but going by what their blu rays look like, I think it would be worth it.
So yeah, I could potentially go for Aladdin and Wizard of Oz (but for that, only if they took it seriously and really committed to it because along with Avatar in IMAX 3D, Wizard of Oz in high def/blu ray is the best looking movie in the world to me).