Definitely agree with Cranium Command. It wasn't much to look at and definitely dated due to the clothing and hairstyles shown, but the script and SNL actors were hilarious, and the way the story was told was a clever gimmick.
I also miss Alien Encounter. I know not everyone liked it. I agree it was definitely out of place in the Magic Kingdom, but the attraction itself was one of the best sensory experiences up to then. Genuinely scary.
This will probably illicit a few "huh"'s, but I miss the Stave Church exhibit. The church is still there, but the actual exhibit about stave churches has been replaced I think last year. Theme parks can get chaotic, even Epcot, yet in that tiny space was a wonderful little place of reflection that most people missed.
Here you leave today and enter the world of yesterday, tomorrow, and fantasy.