I hit Whistler pre-Christmas every year. My sister lives in Vancouver so I usually ski 4 days at Whistler and do a few in the city. Typical conditions are excellent and I think it's the closest to a mid-December sure thing as you'll find on the planet. (Utah's Cottonwoods are pretty reliable, too). November and December are the base building months where it usually dumps fairly heavy snow several times a week. Don't expect to see much sun and don't be surprised if you get completely shut out on the Peak Chair. Expect to spend much of your time at mid-mountain where the trees give you some contrast. Last year was a very bad snow year and there was still a fair amount of terrain open.
On the Blackcomb side, they usually don't open the Glacier express 'til Xmas and they don't patrol below the glacier T-bars. The steeper tree runs off the Crystal chair will also have ropes with ski at your own risk signs.
I've stayed at the Listel Best Western a couple of times when I couldn't score a free place to stay. At $99 CDN on the pre-Christmas rate, it's a pretty good value. Basic hotel room like a middle grade Mariott, hot tub, minimal services. It's a 5-minute walk to the gondolas and you're right in the center of things. There's another $99 CDN hotel up next to the Chateau Whistler but I've never stayed there.