I have one of the 21" models here:
The eBags Brand - Top-Rated Bags Carry On Luggage and Suitcases - eBags.com
I also used to use a duffel bag similar to this (lighter overall than the luggage, didn't have to drag / roll it through the snow, if you park a long way away, then rolling can be easier than carrying):
http://www.ebags.com/category/sport-...rigin=left_nav