Agree that GF is a must see, especially the giant gingerbread house. The displays at Poly and Contemporary are not as exciting, but you could do the monorail loop to catch all in one trip. Could work it around a dining reservation, or during day at MK - could use as a midday break, or if leaving early on
MVMCP night. Wilderness is beautiful, and others mentioned, you could hop the boat to the Fort after to catch the wagon ride to see the lights(if there at night of course - it does have a fee) - could also be done as part of an MK day. We love AKL at any time of the year, and think it is great to experience - similar set up to WL, if you could not do both. It is a 5 minute bus ride from AK, so could also do as a break midday, or at the end of the day. As PP mentioned above, you can do BC/YC/BWI as a group as well, again as a break at Epcot or around dining or Boardwalk night plans. Love the carousel at BC. Here is a link which highlights some of the resort holiday decor:
https://www.dadsguidetowdw.com/christmas-in-disney-world-hotels.html For the wagon ride, you just show up, a lot of people jump on after HDDR show since it is right outside Pioneer Hall. While not regarding the resorts, seeing the castle lit is our favorite activity! Have a great trip!