When your feet are aching or you just need to relax a bit but don't want to leave the park, one of the best ways to overcome that little dilemma would be to head over to Tomorrowland and climb aboard the Tomorrowland Transit Authority People Movie(usually referred to simply as the TTA). The TTA is one of the best, most relaxing (and overlooked) attractions in Walt Disney World.
Located in the heart of Tomorrowland, the TTA is a 10-minute overhead journey (a "Super Skyway Tour") through the land and offers a glimpse inside and around the various attractions in the area. Powered by a linear-induction motor system (which I can't fully describe the logistics of), these trains travel along at a gentle 10 mph. Along the way it passes by Extra-terror-estrial Alien Encounter, Carousel of Progress, and gives an inside glimpse of Space Mountain, Buzz Lightyear's Space Ranger Spin and even Mickey's Startraders gift shop.
The attraction is what I call a "constant loader", meaning that once you head up that escalator ramp to get on the ride, you find the platform in constant motion, with riders getting on arriving cars and other cars beginning their journey. This cuts down on the wait time, but being the overlooked attraction that it is, there isn't much of a wait to begin with, which is a good thing. The little overhead chimes that play before the speaker informs you of where you are within Tomorrowland can be heard all over Tomorrowland as you walk around and I usually find them playing over again in my head later on in the day. In addition to giving the nervous a glimpse inside Space Mountain to see what its all about, it allows those wanting to ride SM a chance to check out the line for it. This way, once the TTA ride is finished, you can head over to SM, grab a FastPass, and ride the TTA again or another attraction until it's time for your ride.
The ride isn't thrilling or particularly fast, but it really is worth riding. It pokes along just quickly enough for you to enjoy the breeze and is just long enough in length so that your tired feet are rested and you can head off to whatever ride or other attraction you like. Sometimes I enjoy riding it several times in succession, since the Disney employees will usually allow you to stay on the train if you wish. Do yourself a favor and don't pass by the Tomorrowland Transit Authority....you'll enjoy it.