I have an article on this subject on skiingmag.com: http://www.skiingmag.com/skiing/travel/article/0,12910,328638,00.html
For big mountain terrain Whistler is the best bet historically. If you're going into Vancouver you might want to leave a day or two aside for Mt. Baker.
Utah is probably the next choice. If this is a one-week or longer trip and you have a car Targhee/Jackson are a 5 hour drive away as backup.
The early season reliability issue can be looked at 2 ways. By Christmas you're looking for consistency, who's in full operation the highest percentage of the time, a category which Targhee wins handily, with Baker and Whistler the next most reliable.
In November you're shooting crap anyway so here you're looking for an area that tends to get its snow in big dumps, so if there is snow there might be a lot of it: Cottonwood Canyons of Utah, Wolf Creek, Kirkwood, Mammoth. This past season all of these got the October dump and were in full operation throughout November. There have been seasons when all of these were rocky past Christmas.
Early December you need to consider both aspects above. But the period between Thanksgiving and Christmas is slow in the vacation travel business and great deals abound (not just skiing, check cruises for example), even at the last minute. If you have time available in the first half of December I would wait until November to see who has snow. The airline seats aren't full either, so you should be able to use your coupons at this slow time on relatively short notice.