-Campy humor of Universe of Energy. Look beyond the old show and respect it's hilarious writing.
-Living Seas. Just walk around the exhibits, don't run out after the ride and Turtle Talk.
-Take the Behind the Seeds tour at the Land. Also they have the best counter service food in all of WDW there.
-Test Track & Mission:Space
-Stop by Innoventions to ride the Segways and build your own rollercoaster in the Sum of Thrills.
-Fountain of Nations
-Do Kim Possible missions in World Showcase.
-Exploring all the countries. It's amazing how much depth and detail there is, yet most people breeze right past them or just look at the shops closest to the main path. Go into countries like Japan, England, etc.
-Catch several shows, including the Japanese drummers, Off-Kilter, and others.
Hope that helps.
Wonders of Life shouldn't be mentioned along with Horizons, WoM, or SSE. Ever. I think people look at it through rose colored glasses.