Forgive the, "never been out west" ignorance but what constitutes a resort out thata way? Not sure I understand the objection to the question/list?
They are ski areas...no lodging at the base area...and the stuff that goes along with having lodging at the base area.
CO Resorts: Keystone, Breck, Copper, Winter Park, Vail, Beaver Creek, Crested Butte, Steamboat, Aspen (all 4) and Telluride.
Ski Areas: A Basin, Loveland, Wolf Creek, Eldora, Ski Cooper, Powderhorn, Purgatory, Silverton, Sunlight, Granby Ranch and Monarch
I'm slowing working my way through all of them. I have to update my top 5 after every trip.