We did the same thing last year and here are the things my In Laws commented on as the things they liked best:
Hoop Dee Doo, HOP, COP, TTA, any boat ride from MK to a resort, the boat parade on Bay Lake, WS at Epcot (but spread out over several days - lots of walking) especially the Voices of Liberty and the drum and bugle group in the American Pavilion, SE, Killmanjaro (sp?) Safarri, F of the LK, WWTBAM, One Man's Dream, Great Movie Ride, The train around MK...
They also loved being left to sit and people watch. They spent a few hours just exploring the shops on Main Street USA, especially the "side streets" with all the details. The Main Street singers were a particular favorite.
- lori