Mid-December can be iffy in really bad years..
My other concern would be price. The Christmas period tends to be VERY expensive in New England. I investigated renting a 2 bedroom condo at Sunday River in Maine with my brother and his wife. The cost would have been $1600 for two nights loding and two days of skiing for 4 people. Needless to say, we bagged that option and instead plan to take a day trip to Sunapee (new and greatly improved under the same management as Okemo) if I even go to Boston during that period. My wife wants to go to Timberline instead, and I'm leaning in her direction.
Interestingly enough, the conditions I experienced at Whitetail in early January were better than what I experienced at Stowe last year during roughly the same period. The reason for this is that Whitetail does a better job of covering its slopes with man-made snow than Stowe. Sounds hard to believe, but it is is true. Many Mid Atlantic resorts have better water supplies than New England resorts and more snow making coverage per square foot of terrain. In short, if we get cold weather, you can count on Mid Atlantic resorts to blow 6 inches per night on nearly every trail. The same cannot be said for many VT resorts. If we get cold weather West Virginia should have some decent skiing in December, but the weather will have to be COLD.
Pete, if you can wait until the last minute to plan the trip, that may be your best bet. Go where there is snow.
Other than that, you might consider Colorado. Believe it or not, you might find a cheaper package to CO than VT during this period--especially with air fares being so low and people being afraid to fly. Keystone and Loveland are already open.
PS I am going to try and ski Snowshoe in later November if it opens. I'll be sure to write a first-hand report for DC Ski if I go.