I would choose the November dates! Without question, those dates would be my first choice!!
The cost will be lower in November and premium prices will be in effect over the late December to New Year's Day dates.
The December dates will have peak crowds. Crowds so thick that often parks close to capacity. Holiday crowds won't arrive for Thanksgiving until November 22nd.
The November trip would allow you to tour the parks and appreciate the decorations as they transform WDW into a holiday wonderland.
Consider arriving a day earlier and you'll likely be able to take part in
Mickey's Very Merry Christmas Party! This after-hours ticketed event in the Magic Kingdom is a highlight of the Christmas season in Disney World. While official dates have not been released yet, looking at last year's dates, it is likely that a party will be scheduled for November 18, 2011.
Enjoy the decorations in mid-November for lower crowds and prices!