I have been to WDW during Thanksgiving and Christmas in the past. My understanding is that all of the resorts are decorated for the holidays. The resorts also have trees that are usually decorated thematically to match the resort's theme. The resorts that I have seen decorated are:
Wilderness Lodge - has a HUGE tree in the lobby that should not be missed
Animal Kingdom Lodge - has a similarly HUGE tree in the lobby with animal decorations
Grand Floridian - has a life sized gingerbread house and other holiday decor
Port Orleans F.Q - many trees all over with lots of purple, gold, etc decor and mardi gras masks
The only question that hopefully someone else can answer is whether all of the resorts have finished putting up their decorations as yet (when I stayed at POFQ it was a few days before Thanksgiving and I actually witnessed the crew come in late at night and start to install the decorations).
I would definitely recommend that you try to make it to the Grand Floridian and the Wilderness Lodge if you only have limited time to resort hop.
Enjoy your trip!