Sorry to disillusion those of you with short memories, but here are 14 years of data for major Colorado areas: http://people.montana.com/~jbraun/coloearly.htm
. For the big areas all average only 20-30% of terrain open at Thanksgiving, with Keystone a little more due to flatter terrain and lots of snowmaking.
Bob Peters has it pretty much right. The Colorado areas will have something because they can always make some snow, but it will not likely include advanced terrain. In the same table note Wolf Creek, which is one of the better natural snow areas, averaging 75% open at Thanksgiving. This is another place with mostly intermediate pitch not requiring deep cover, and note that WC's 75% average really means close to full operation in 75% of seasons and completely bare the other 25%.
Brighton and Alta have a similar profile to Wolf Creek, except that Alta has some steeps that take a lot more to cover.
I have very detailed records for Mammoth, and it is 50% or more open on December 1 in only about 1/3 of seasons. Mt. Baker, Whistler and Mt. Bachelor would have the best odds of the West Coast areas, and would have considerably more terrain available than the Colorado areas in late November most seasons.
You can raise your odds considerably by shoving that trip forward a couple of weeks into early December. The travel business is very quiet and you can get good deals, perhaps at the last minute when you can see who actually got snow in November. Last year was a good example in that the Cottonwoods were marginal through November but got hammered at the beginning of December.