All I have to offer is a lot of repeat suggestions, but what the hey:
TTA is the best, hands down. I could just sit on here for hours going around Tomorrowland-- in fact, I have, it was great, and would highly recommend the experience to anyone.
CoP is good too, but then I get that bloody song stuck in my head for the rest of the day.
Philharmagic is just one of those experiences that reminds you why you love Disney. Surprises around every turn, classic Disney characters, good natured and good humored. One of the two sensory theater experiences I will willingly sit though at WDW. (The other is Muppets 3D.)
SSE in Epcot is another one I could loop on for hours, although I haven't seen it after the refurb yet. I'd be willing to bed that it's still a good one, though.
Gotta agree with One Lil Spark too-- Impressions du France is *awesome*. Comfy chairs, fantabulous score (I'm a bit of a music geek by day), and some great film. (I do hope they update the movie though like they did in Canada-- you definitely get a sense of its age at times.)
Living with the Land is worth it just to see the Mickey pumpkins and the hidden Mickey in the test tubes in the lab. Good, green Disney fun for everyone on this relaxing boat ride.
Heading over to MGM, Muppets is simply classic. A must do on every trip. (See Philharmagic for other reasons.)
Last but not least over at AK, the Finding Nemo musical is probably my absolute favorite show down at WDW now. Entertaining from start to finish, the music is FABULOUS, and some very clever staging. You really feel like you're watching a Broadway production. The long wait you have to wait outside for the show because it's rightfully so popular isn't a fantastic "cool down, rest your feet" experience, but boy are you in for a treat when you get inside the building.