Just felt like adding Beaver creek, CO, yes the resort is very expensive but if you have the $$$ it's a great resort for learning. This resort over grooms its runs, so conditions are always pretty good for learning, they also offer steeper terrain for those who are more experienced. Most of their main runs are extremely wide and the skier density is pretty low, you are also going to find less crowds than Breck, Vail and definitely Cooper. Granted I didn't stay at their village, but I do have to say that the place is amazing (a lot of money going around, restaurant, activities ect.)
If you guys are on a budget I would recommend Loveland, CO. That place has it all vibe, cool terrain, no crowds, friendly people and best of all an affordable price. I am not sure how beginner friendly it is, but there are a good amount runs that I would consider good for beginners. They are not as wide as the runs of Beaver Creek though.
With Cooper I found the resort to be great but my main complain were the crowds, men that place gets crowded. Breck I usually avoid it for the same reason.
I do have to agree December can be a scary month, I am not sure where but I read somewhere that Colorado gets a big dump October/November and they get a dry spell. The key issue is how long does it last, usually it's not that bad, but this season had me second guessing how the conditions in early January were going to be.