From a crowd-avoidance perspective...
Avoid (to the best of your ability) anything scheduled that is almost guaranteed to bring a larger crowd to the parks.
Like holidays when schools are closed (Thanksgiving weekend, Christmas week),
Pop Warner week (usually beginning of December), especially if you plan to stay in the value resorts,
Veterans day weekend,
"Jersey Week" - generally the beginning of November when schools in NJ are closed for teachers convention.
Many will argue that crowds are "manageable" during some of those times. But given the choice, if I KNEW that there would be an extra few thousand people there, I'd pick a different week.
The weather in December is all over the place. I can't speak for November. We were there last December and had a nearly 50 degree temp swing during the course of the week - 85+ degrees and sticky humid for a few days, then a cold front moved in and it was in the low 40's in the morning, warming to a balmy 65.