Hi Serina,
You will have such an amazing time with your little princess!!
You will find something at each of the parks that will suit you and your little one.
My choices in order for four year old fun would be the Magic Kingdom, Disney's Hollywood Studios, Disney's Animal Kingdom, Epcot.
It depends on how many magical days you are spending at Walt Disney World.
A few must-do's would be
character dining, and a visit to the
Bibbidi Bobbidi Boutique
Don't forget to pick up an autograph book, you won't want to miss getting autographs from your favourite characters!!
If you have any other questions, please let me know.
Wishing you and your little princess a very magical vacation!
Carrie