Things I like to do that some folks overlook:
Living with the Land boat ride in The Land. Peaceful, educational, and just kinda cool. Even in busy season, I've seen lines of less than 5 minutes.
Innoventions East - Fantastic Plastic works, and some of the interactive environment and business games. Just a fun way to spend some time, and it's air conditioned for those hot days.
American Adventure - the walk-through Americana museum/display...there are some very cool things in there - lots of history.
Japan - always like to stop and listen to the Taiko drummers at least once a trip.
Canada - Love the 360 degree movie...the old one was even better, but the new one is still beautiful. And of course, sit in for a show or two with Off Kilter...fantastic and highly skilled band who plays a variety of rock/folk/irish/scottish tunes.
If you're willing to pay extra, the Land's greenhouse tour is also very cool, and very educational.
Some folks may not like the educational/historical stuff as much...but being the nerd I am, I loved that about Epcot when it first opened, and it quickly became my favorite park. They've watered some of it down and added more 'action' stuff to keep people's attention spans in a changing world, but I still like to seek out the stuff that educates about history, cultures, and customs. Talk to cast members, especially the guest workers from all of the various countries - they love to share info about their homelands, cities or towns, geography, history, etc...and are very friendly people.