I have some doubt much of Breck's "Big Mountain" stuff will be open then, much less A Basin. At Breck, lapping the TBar or imperial express, or 6chair is usually a good time but it gets bumped out fast. It really helps to be a strong bump skier at Breck if you don't ski much park. At A Basin, Upper East Wall usually opens in February or March and all the other stuff until then is mini-golf-cliffs, steeps, and bumps. Once again it helps to be a strong bump skier.
Surprisingly, I find Keystone's hike-to terrain pretty fun. They range from 400m to a mile or two and on a good day will be powder and until the next storm won't get too bumped out and you can really get ripping if you know how to ski chunder and crust well.
I don't really have any knowledge of other summit county resorts so I can't weigh in on those