Back in '92 when I was on the college program (Inside the Magic: The Special Effects and Production Tour), there were several ideas that I came up with...
First, Tiki Birds was down for its re-worked show (which should have been put down). So the idea that I had was that the Tiki Birds should be moved to the Disney-MGM Studios and given a Hitchcock twist - at the end of the show, the birds rise up and attack the guests.
The next idea, was to merge the Hall of Presidents with the Frontierland shooting gallery. (No further comment please, I know it was a SICK idea).
Another idea was to have the 4th gate themed after the great wars of the modern era. (This was during the DAK rumors, where everyone knew that the land had been cleared, the nighttime lighting determined, but no announcement.) One of the attractions would be a Jungle Cruise type of attraction where you're on a tour in the deepest, darkest regions of Vietnam when you accidently sail into a combat zone, before you can be escorted out of the zone, planes start attacking you complete with straffing runs and the such (a la the special effects water tank). In the center of the park would be a mountain, that of course was the parks icon, the NORAD mountain. Everyone entering the park enters through the mountain where they're given a tour of NORAD, during the tour alarms go off - ITS A THERMAL NUCLEAR ATTACHK! The military goes DEFCON1. Missile tracks light up on the boards showing the destinations of several inbound ICBM's (curiously they're not headed to NY or LA - they're headed to Orlando & Anaheim). When the missiles are just seconds away, everything goes dark and the works 'SHALL WE PLAY A GAME?' appear on screen and someone comes running in screaming that it was only a simulation.
Needless to say, I'm not an Imagineer.