Aside from some empty space in Epcot, I think WDW is (or was) perfect the way it is. I would prefer that all investments went into maintenance and number of CMs.
Disneysea in Florida would be cool. Indy ride from california and a space mtn refurb. I know we have the original but once tron opens space mtn will feel very dated... maybe it could be steampunk themed like the original version in france.