Hi Patricia!
I definitely recommend the
Mickey's-Not-So-Scary-Halloween Party (MNSSHP)! I've been taking my kids to Walt Disney World in September for years and MNSSHP is a must-see!
Your son will also love Fantasyland at the Magic Kingdom! There are new attractions in Fantasyland from the expansion and he won't want to miss either the classics, such as Dumbo, Peter Pan and It's a Small World or the new adventures, including the Great Goofini (re-imagineered Goofy's Barnstormer) and train station.
A few other must-see attractions for a four-year old boy include:
1.
Disney Junior - Live! On Stage at Disney's Hollywood Studios. He can meet Jake and the Neverland Pirates and experience Mickey Mouse Clubhouse, Handy Manny and Little Einstein's.
2. Toy Story Mania at Disney's Hollywood Studios.
3. Eating with Mickey Mouse at Chef Mickey's at The Contemporary.
4. Kilimanjaro Safari and Animal Kingdom.
5.
The Seas with Nemo and Friends at Epcot.
Please let me know if I can help you with anything else at all!
Magically,
Stacy