Hi Jennifer,
All of the resorts are decorated for the holidays, but some more than others. There are two resorts that come to my mind for Christmas decorations: Disney's Grand Floridian and Disney's Wilderness Lodge.
The
Grand Floridian is home to what many guests consider to be the most admired Christmas tree at the Walt Disney World Resort. It is Victorian in theme and is absolutely fabulous. The famous life-size Gingerbread House is also spectacular! You can actually buy snacks, including gingerbread, at the house.
Personally, I love the
Wilderness Lodge and I think it "screams" Christmas. There's nothing like sitting in a rocking chair by the fireplace in the main lobby while enjoying the larger-than-life Christmas tree and Christmas music. The Pacific Northwest theming outside is also particularly nice for Christmas. During the holidays, you can also take a "sleigh" ride directly from the Wilderness Lodge. It's also very easy to get to Fort Wilderness Resort & Campground via boat from the Lodge. Historically, guests staying at Fort Wilderness have put up amazing Christmas displays. If you stay at the Lodge, I highly recommend taking time to visit nearby Fort Wilderness.
If you stay at another resort, I still recommend visiting these two resorts. Also, If you're in the Crescent Lake area between Epcot and Disney's Hollywood Studios, you should visit the Beach Club and Boardwalk Inn as they also have great Christmas decorations!
Enjoy planning your vacation and write back if you have any more questions!