Our two cents worth:
If MK has an early entry day when you are there, take advantage of it for your dd.
We do for our ds's-and they usually ride everything in Fantasyland twice before the park opens to everyone--and I bet your dd will want to do everything in Fantasyland.
Also, Buzz's Space Ranger Spin, Toontown, Pirates, Alladin, Mickey's Philharmagic, and Jungle Cruise are good for young ones.
My boys also love the Indy Race Cars.
In MGM: Voyage of the Little Mermaid, Bear in the Big Blue House, Muppets 3D, Honey I Shrunk the Kids play-yard. Beauty and the Beast and Fantasmic are also excellent.
In AK: Festival of the Lion King, Tarzan Rocks, and the Boneyard are far and away my kids favorites (ages 4 and 6)
EPCOT: Imagination is their favorite. The Land is good if you daughter is lucky enough to get picked to make cookies.
Don't try to overdo-as the others mention. But as far as my kiddies go, the above are requirements every time we go to WDW. HAVE A GREAT TRIP!!!