It's my understanding that they decorate each resort at Christmas (I haven't seen them all personally

). I know that All Star Music this Christmas was decorated. The decorations match the theme of the resort, so at ASMu, the ribbon on the wreath was a piano keyboard, and many of the ornaments were musical notes, treble clefs, etc. It was really neat to see how they tied it all in to the resort theme.
We looked at the Grand Floridian on that trip as well. Their decorations were victorian, to go with the hotel theme. The tree is spectacular - three or four stories tall with ornaments 2 or three feet tall, and a gingerbread house taller than the people standing around it. Obviously, ASMu didn't have anything on that scale, because they don't have the same type of lobby. But the tree and wreath that they had at ASMu with it's themeing was really nice, in our opinion, and we felt it was really festive.
We loved our December trip - after we got back my husband confessed that he thought something to the effect of "Why would someone plan the timing of their trip around the holiday season." (That wasn't what dictated our timing - the holiday was happy coincidence, but he knew that some people do). But after going, he has said more than once how wonderful it was to see all the parks at that special time.
BTW - crowd levels were great in early December.