Hi Amanda!
Welcome to the Moms Panel and thank you for sending in a question; it's nice answering a question from a fellow citizen of Maryland.
I have a 5 year old son and he loves all of the theme parks and the water parks at Walt Disney World. His favorite park is the Magic Kingdom, followed by Disney's Hollywood Studios, Disney's Animal Kingdom, and finally Epcot. His favorite hotel resort is the Animal Kingdom Lodge; he loves the idea of seeing animals right outside the hotel.
My son enjoys Disney Character Dining. One of his favorite things to do at Walt Disney World is eating at Chef Mickey's in the Contemporary Resort. My family also enjoys eating in 'Ohana in the Polynesian Resort and the Whispering Canyon Cafe in the Wilderness Lodge. Be sure to make Advanced Dining Reservations (ADRs) before your trip. ADRs can be made 180 days in advance. Walt Disney World has some amazing restaurants and some of them book up very early. Reservations can be made on-line
here.
With a 5 year old, take things slow and visit the attractions that he seems to be most interested in. Also keep in mind that one of his most favorite activities might be just swimming in the hotel pool. When we stayed at the Beach Club Resort, I had a lot of trouble getting him out of the pool. Of course the Beach Club's Stormalong Bay with a sand-bottom pool is the best pool on property.
Enjoy planning your vacation and write back if you have any more questions!