Depending ont the age of you son, last year my DS was able to create a Christmas Tree ornament using Ostrich eggs. He had a blast. I think the cost was $2 which went to the conservation fund. They did it in the lobby area -- you might check for activities like these. And, they also have a variety of other kid activities that are very enjoyable. This is a beautiful resort.
Another thing to check out is the entertainment in the GF lobby area. The gingerbread house, which they create from scratch each year, is amazing. They use it as a gift snack shack. And, they continuously have a variety of Christmas entertainment in the lobby. The tree there is also gorgeous.
Also, many of the resort staffs create Christmas villages at the hotels. There will be one at the AKL and I know the BC and YC as well as Boardwalk all have different things the staff creates for the lobby area. It is worth taking a trip to the hotels to check out the decorations. Disney does Christmas in a spectacular way.
Oh yes, and at DTD they have different groups entertaining, too, plus a tree lighting ceremony ... and one at MK.