Hi Anita,
How wonderful that you will be celebrating 2 birthdays during your trip to Walt Disney World!
If you are looking for something different to do, I would recommend taking part in a Tour or Special Experience whilst at each park.
You can see what is on offer at Magic Kingdom
HERE and Epcot
HERE
As you can see there are lots of different options available and you will have an idea of what your Partner and Son may enjoy depending on how daring they are and their individual interests.
Another thought would be to make an advance dining reservation at a
signature restaurant. Specialty celebration cakes are available for an additional charge and should be ordered 48 hours in advance by calling 001 (407) 827-2253.
I hope that this has given you some ideas but please come back and ask me another question if I can be of any further assistance.
Wishing you all a magical holiday!