I forget where I found this link a while ago, but ShermansTravel rated the top 10 apres ski scenes in the world. In the US they ranked Aspen, Killington, Tahoe and Telluride. Whistler also made it.
Cheers! 10 best après-ski scenes - Travel - Seasonal Travel - msnbc.com
I've only been to Aspen and Killington but personally I love Aspen. Just find the people to be super chill and they have really good public transportation (my sister has a house in Basalt so all I have to do is hop on the bus so I didn't have to worry about driving). All the supposed hot spots in Killington had insane cover charges so I preferred the dive bars. At any rate, check out the article - if anything it's a fun read.