At this time of year, probably the prairies somewhere - Winnipeg? Steinbach? But, be prepared, the winter there can be BITTER (-40C! and windy as well..) However, generally, when it is that cold, the sun is shining and it is great flying wx. If you were on a time schedule, then I'd probably go there. Scenery-wise I'd probably head for the West Coast, but our cost of living is pretty high, and in the winter, it rains a lot, so there's not a whole bunch of flying..
good luck.