EVERYTHING!!!!!!
We have a 7 yr old boy and 12 yr old girl and they just love everything!!

They tell me their fav park is Epcot with Soarin & Mission Space but it will depend on the type of kids you have. My eldest just loves the big rides like Expedition Everest (AK) & Space Mountain (MK) whereas the 7yr old is not into that at all
These are their top rides:
Magic Kingdom : Pirates of the Caribbean, Big Thunder Mountain, Haunted Mansion, Space Mountain & Buzz Lightyears Space Ranger Spin.
Epcot: Mission Space (green channel) & Soarin
Animal Kingdom : Expedition Everest, Primeval Whirl, Nemo stage show
Hollywood Studios : Star Tours, Motor Stunt show (not sure of the name), Rock n roller coaster & Tower of Terror
I know I have probably missed a lot as they just love it all
This is only Disney.........then you have Seaworld, Aquatica (opens in March), Universal & Island of Adventure. The list is never ending which just means more trips across the pond
Tracey