Aspen is not crowded. It is nothing like Vail or Summit county. Expensive yes. 4 mountains to chose from and the best Apres ski scene in the lower 48.
Big Sky also has Moonlight. I think it would be a pretty ideal place. Maybe Whitefish would be another choice?
Steamboat is a great ski town. Yeah one mountain, I am sure you'd be more than entertained there. Book a day of cat skiing while you are at it.
Jackson, one hell of a mountain. They do have plenty of runs for all abilities. Just cause it has the gnar doesn't mean you have to ride it.
Telluride, kind of like Aspen, but a little more remote, still pricey. Stunning scenery there for sure.