Hi Amory!
Christmas time is a great time to tour the resorts! You're right: every resort is decorated - but some more than others!
Personally, I tend to tour the resorts around the Magic Kingdom area with the Grand Floridian, Contemporary and Wilderness Lodge as my favorites. We also like to visit the Beach Club, if we have time our our Epcot touring day.
The Grand Floridian's features a Gingerbread House that is enormous. Cast Members sell Gingerbread houses and shingles from within it! The Disney Parks Blog even had a great
post about it which featured the house's ingredient list!
The Contemporary features a Gingerbread Tree with small gingerbread people who are reminiscent of the dolls in Its a Small World. The Wilderness Lodge (take the boat from the Contemporary to get there!) is beautiful. The lodge's lobby features a Christmas tree that must be 4 stories tall! On select evenings bell ringers often are performing Christmas music too!
Over at the Beach Club, a chocolate carousel is featured. It even celebrated its 10 year anniversary! Check out this Disney Parks blog
post to read more about it.
Hope this helps!