Hi Lisa, Congratulations to your son on his achievement!
Disney World is the perfect place to celebrate all of life's big (and little) moments. I have a few suggestions for you:
If you'd like to order a special cake to surprise him with at dinner one evening, you can call: 407-827-2253 to order a custom cake. Also, if you have dinner reservations already for somewhere and want to make that evening extra special, call 407-WDW-DINE. Provide them with your confirmation number and let them know what you are celebrating. You can request that they sprinkle the table with Mickey confetti or other options. We had the metallic Mickey confetti for our Anniversary and it was extra special.
You might also want to browse this link:
HERE. It has oodles of suggestions for ways to customize your celebration.
Another idea is to call Disney's Dream Makers at:
407-827-3505. They specialize in helping to make special moments even more magical. Let them know about your sons wonderful achievement and ask them for ideas on how to celebrate. I think you'll be very happy with the ideas they come up with. This is a link to some of their offerings: HERE. Please note that if you don't see something that catches your eye, they are more than happy to help you customize something just for your son.
Hope this helps and have a magical trip!
Kaylene