Didn't get through all of the thread, but didn't see anyone mention IF YOU HAD WINGS - Delta Dreamflight?? That was always one of my favorites. I can still hear the song in my head.
My memories for most of these gone-but-not-forgotten attractions are from 3rd grade ('83) and 8th grade ('88). So some are vivid and some are just disjointed impressions. Fun to think back on those family vacations, though!
If You Had Wings / If You Could Fly (trips: '83 & '88):
For that one, I could only remember the "traffic cop" and "bon voyage" video segments and the wind tunnel at the end. But I clearly remember my dad pointing out the fans on the sides of the track inside the tunnel and seeing that we were still going about 2mph!
20,000 Leagues Under the Sea (trips: '83 & '88)
Figured out that the Nautilus vehicles never really submerged on my second trip, which made it even more curious as to why the seats and floor were wet (?). Must have happened to have rained that day... For the life of me, I don't remember anything specific about the underwater scenes.
Mission to Mars (trips: only '83, that I remember)
Large circular chamber with a video screen on the floor in the center, right? Signature effect: your seat cushion would shake and sink down during the 'high G' take-off.
I remember much less about the Epcot attractions. IIRC, we skipped Epcot on the first trip and rushed through it on the second. Wish I had access to those pictures right now...
Thanks for the memories!