Christmas has been really iffy the last few years, I would only consider one of the higher resorts with, as btfl says, an option of something lower down if the snow turns out to be good and you have some grim days. Les Arcs ticks both boxes, as does Avoriaz as you can get down to Morzine if needed, I'm sure there are others. No idea how suitable they are for beginners.
What's the age range? Christmas can often be pretty grim and cold, and little ones seem to feel it more. We've avoided it for this reason, but my brother usually goes, and says that the kids usually have a very short day, often half day or slightly longer because they are getting so cold and tired, and then spend the rest of the day indoors in front of a DVD, while the adults get some runs in, which may be a good or a bad thing! You considered Easter?
