In no particular order (other than by theme park)
MK-Haunted Mansion, POTC, Tiki Room, CoP, Jungle Cruise, HoP (Do we really need the current Commander-In-Cheif to drone on and on...this goes for Clinton and Bush), Indy Speedway (totally revamp the track ala Disneyland).
Epcot--HISTA, Canada, SSE, Malestrom (longer, please).
DMGM--GMR, Backlot Tram Tour, Millionaire (replace it), Sounds Dangerous (ditto), Star Tours (new film).
DAK--Rafiki's Planet Watch (make it worth repeat visits). Dinosaur (make it more than an over-priced dark ride).