At Magic kingdom you can ride the 3 big mountains. When you get to the park hop on the Walt Disney World Railroad on Main street. If you want to do the 2 big mountains get off on the first stop U.S.A. Frontierland. There you have Splash Mountain and Big Thunder Mountain Railroad. Please get a fast pass for that since the line is very long and you're going during the high season. After that you can get back on the Railroad and get off at the next stop which is Mickey's Toontown Fair. Just walk a little and it will take you to Space Mountain. Other rides to do are Mickey's Philharmagic, It's a small world, The Haunted Mansion, and Pirates of the Caribbean. They also have a lot of rides for the kids.
Don't forget to see Wishes. (the fireworks)
At Epcot you can ride the big attraction Soarin'. The line is very long so please get a fast pass. You also have Test Track and Mission Space. You can do Mission Space if you want to but some people get sick after the ride.
(You don't want to mess up your day for a ride) For the kids you can take them to "The Seas with Nemo and Friends" and "Honey I shrunk the Audience". After that you can go the World Showcase. There's a lot to do there like shopping, drinking and eating. Every Pavilion has a restaurant. There's a ride inside Mexico and Norway. And don't forget to see Illumination. By far the best fireworks at Disney.
At Disney MGM Studios you can ride the 2 big attractions, "The Twilight Zone Tower of Terror" and "The Rock n' Roller Coaster". That ride goes from 0 to 60 in 2.8 seconds. You can also do "Star tours-the ultimate Star Wars thrill ride" and watch live shows like "Lights, Motors, Action! Extreme Stunt Show" and "Indiana Jones Epic Stunt Spectacular". At night you can see the fireworks "Fantasmic".
At Disney Animal Kingdom you can do the new big ride "Expedition Everest". You might want to get a fast pass for that since the ride is still pretty new and everyone wants to ride it. Next to it you have "Kali River Rapids". Please take some extra clothes (you can rent a locker) because you are going to get wet. Not far away from there you can go to "Maharajah Jungle Trek" to see a lot of wild animals including 3 big tigers. You can also do the "Kilimanjaro Safaris" if you want to see Giraffes and other wild animals. For the little ones you can take them to Dinoland. Don't forget to do "It's tough to be a bug" Oh and the park closes early.
If you need any info on dining at the park just let me know. Are you planing on staying at a Disney Resort? Or are you staying outside of Disney property?
If you stay at a Disney Resort you have access to the Disney shuttles. They can take you anywhere including to Downtown Disney.
I hope you have a great time with your family.