I agree, the weekend of December 15th or the 16th would be great. You couldn't schedule it for the weekend of the 22nd, as a lot of people could be out of town then, seeing relatives, or otherwise incapacitated .

The only hard part is the timing of it. We're all in different timezones, as is usually the problem, so you'd have to figure out a good midday time that would fit all of the applicable zones.

I'm all for a Christmas party though, let's do it!