We have SO many favorites, but the things I most enjoy with my 10 year old...
MK:
Splash Mountain, Space Mountain, Tea Cups (and taking pics of kids' huge smiles as Dad spins them crazy fast), Haunted Mansion, Pirates of the Caribbean, Peter Pan (nostalgia that she doesn't roll her eyes at!), and Happily Every After Fireworks
Love the tables outside Plaza for a snack with the castle behind you (see my profile pic from our very first trip when my now 10 year old was 3)
Epcot:
Test Track, Soarin', caramels in Germany, Christmas shop in Germany
Animal Kingdom:
Everest
(we are frequent zoo visitors and have been to several wildlife ranches at home, so AK doesn't do a whole lot for us)