I can't tell you how many times I have been during christmas. I love it, it is so beautiful there. You can try going to epcot at night for dinner all the resturants around the world showcase are great. I love mexico, japan and canada. And then you could stay for illuminations and they have an extended version for christmas time. One thing is for sure, make sure you bring lots of film for your camera because its the best place on earth plus more at christmas time.
I will be down the first week of dec. can't wait.
Hope you have a great time
P.S. Japan is great the cook right in front of you and when you have a fun chef it is quite a show