Hi Shannon! Welcome back to the Moms Panel! Looks like you have been doing your research,
Rider Switch is a great option for families traveling with small children. I have two young sons three, and four years old, which makes this service is an essential part of each vacation. You can find a list of attractions that utilize this service in the above link.
Magic Kingdom will have the most attractions your family can experience together. Your little one may even be tall enough to experience Tomorrowland Speedway which has a height requirement of 32 inches, or the Barnstormer which has a 35 inch requirement. My son at two years old was tall enough for both and really enjoyed them. Be sure to take time for yourself to conquer the three Disney mountains, Space Mountain, Splash Mountain, and Big Thunder Mountain Railroad which are Disney must dos.
At Epcot your family can enjoy Turtle Talk with Crush, and The Seas with Nemo and Friends! Be sure to leave some time for the adults to enjoy Soarin', Test Track, and my husband's favorite Mission Space.
At Disney's Hollywood Studios, and Disney's Animal Kingdom you will find a lot of height restricted rides, but they are ones you will not want to miss. Star Tours, Twilight Zone Tower of Terror, Rock' n' Roller Coaster, DINOSAUR, and my personal favorite Expedition Everest. Don't feel like your son will be left out at these parks, they have plenty to see for little ones including Kilimanjaro Safaris, Finding Nemo-The Musical, and Disney Junior Live on Stage.
Your WHOLE family will have a blast I just know it! Wishing you a magical birthday vacation!
~Jen