Since the attractions are kind of an obvious thing that most people like, I'll go with some of the lesser things I enjoy:
-Walking around the Boardwalk, taking in the nighttime entertainment
-Sitting on the curb while waiting for a Magic Kingdom parade and just people watching as everyone goes by
-Visiting different resorts
-Relaxing by the swimming pool
-Seeking out rare/less common photo opportunities
-Riding the monorail
-Taking in the atmosphere at each park - sometimes just walking around and listening to the music is as much fun and as magical as the attractions