I was counting the vacant buildings when I was at the park on Sunday.
1. The Wild Wild West Stunt Show stadium
2. The old Murder-She-Wrote/ Hercules&Zena building
3. The back half of the Shrek building (remember Hitch had 3 rooms, it does not look like they used all of the space for Shrek...although they should have with the waits that film is getting)
The only really great space is the Stunt show stadium, which with MGM adding the auto stunt show, and USF being without a stunt show, I think that will be the next thing added.
The old MSW/H&Z building is not great space, if you remember, it was like Carousel of Progress, only you had to move between the theaters yourself. Besides a special effect show, I don't know what could be put in here
The Earthquake building is large, but it is long, not tall.
I think, that besides adding a show back to the Stunt Show arena, USF is not going to add much for a couple of years, as they have just added 3 new attractions. IOA, which has not had anything new since the kiddie ride and coaster a year after opening, will probably be the focus of the next big attraction.