Hi Emily! Thanks for bringing your question to the Disney Parks Moms Panel. Vacationing during the holidays is absolutely magical. It is my favorite time of the year, and Walt Disney World never disappoints with the lavish decorations and special holiday offerings.
I just looked at un on-official crowd calendar from www.undercovertourist.com, and both weeks look like they have a moderate crowd level. I have personally traveled around the same time as your December dates, and I've noticed that the crowds weren't that bad during this time. Actually, if you plan on taking advantage of Extra Magic Hours, the crowds are relatively low once the parks close for day-guests. I specifically remember quite a few nights during Extra Magic Hours where there were hardly any people in sight. It made for some treasured memories that I will never forget.
If I were you, I would choose the November dates because most of the Christmas decorations will be out by this time, and you can catch the
Epcot International Food and Wine Festival before it ends on November 16, 2015. This way, you can join in on the holiday festivities and enjoy one of my favorite 'festivals' at Walt Disney World. Also, on select nights in November and December you can attend
Mickey's Very Merry Christmas Party. This is a separately ticketed event at Magic Kingdom. I got the opportunity to attend last year and it definitely put me in the holiday spirit.
I am running out of space, but no matter which dates you choose, I hope you h
ave an amazing Walt Disney World vacation during one of the most magical times of the year.
If you have any more questions, please feel free to stop by and we'd be happy to help.