I love all the attractions, so it's hard to choose.
But, favorite, must-do non-headliners for me are WEDway (TTA), Rio De Tiempo, Spaceship Earth, CoP, Sounds Dangerous - ones I miss & would like to do again - Cranium Command,Timekeeper, The Original Tiki Room,Mr. Toad, Alien Encounter, Food Rocks & Kitchen Kaberet.
Other non-headliner things I enjoy are the Kristos, Ice Station Cool, the sound booths at Conservation Station & the Fountain of Nations.