In Epcot, we've been bypassing Ellen's Energy Adventure (can't remember what it was previously called) for 24 years (but look forward to checking it out next time). I haven't been inside an Innoventions building in just as long (again, something we plan on doing next time). We've never seen the Epcot World Showcase movies in Canada, France and China (typically in too much of a hurry or too tired), or the Lion King film in the Land Pavilion (saw it on Youtube and thought it would be a waste of time to take the family to see it).
In the Magic Kingdom, we'll NEVER do Stitch again (ugh, we were simultaneously bored out of our minds and completely disgusted). We've also never been on the Astro Orbiter (I'm the only one in the family who has any interest and the line is too long to bother).
In Hollywood Studios, we haven't seen Beauty and the Beast (we will next time) or the Lights, Motors, Action show (or Fantasmic, for that matter -- too far past the kids' bedtime if we want to be up for rope drop the next day). We may do Fantasmic next time. We've bypassed the Art of Animation since 2005 because it didn't impress us the first time around.
In the Animal Kingdom, we haven't seen It's Tough to Be a Bug, Nemo, or Festival of the Lion King (all are on the schedule for next time), Flights of Wonder (we have a terrific bird show at our local zoo, so nobody's interested), Kali River Rapids (no one wants to get soaked to the skin and we've seen the "action" or lack thereof on Youtube POV videos) or Primeval Whirl (nobody in the family is fond of whiplash). We do everything else there on every trip.