Jill,
Wow, that is a stumper. There are so many good choices, it is hard to decide. I will give my opinion, and you can select from a few choices;
Deluxe Resorts
Wilderness Lodge. This place just seems Christmas-ey. The warm and comfy ambiance of both the public areas and rooms is perfect. Big roaring fires, warm log cabin decor, and a gigantic Christmas tree in the lobby make you feel like you are going to be walking out onto a snow-covered grove of pine trees to see Santa in his sleigh.
Grand Floridian. The gingerbread house that they build in the lobby is so big that they run a store from inside of it that sells (guess what) gingerbread houses!
Moderate Resorts
Coronado Springs. I was there back in December, and it had a festive mood that I think edges out the others.
Value Resorts
I don't think there is enough different here between the choices to pick one over another.
I hope that this helps?
If you have any follow-up questions, just ask me directly from my bio page!
Have a magical vacation!