You'll have a great time. Dec. is when we always go. I've been at other times of the year, May, June and I love Dec. the best!!
Crowds are low and the Christmas decorations are out of this world!!
Yes, WL is beautiful at Christmas, but so is everywhere else on Disney property at Christmas time. I'd definately stay at BCV and visit WL. Of course you could do what Mrs. Snowgod said and try at the 7 month window or even split the trip. But VWL is secluded and you have to take the busses or boat everywhere. You know you can walk to Epcot and MGM.
Either way, have a great time!