My dh and I just did this last Thursday night. (We don't have kids either, btw.) Loads of fun even in the cold. Marshmallows over the fire, singalong, then the movie. All the kids there seemed to be having a terrific time.
The camping board keeps a thread going near the top where they either list the month's movies or have a link to a site which does. The movies are usually posted for the upcoming month at the end of the previous month. If you don't have time to check the movie schedule before you leave, you can always call WL when you get there--they have the movie schedule.
We weren't staying at FW or WL, but we took the bus over there from DS-MGM, and were able to catch the bus back to MK on a night when they were open late, so it all worked out smoothly and quickly.
We had a great time and intend to do this again when we're back in the World.
--miffy--
ps: The holiday decorations at FW were awesome!