I'm HERE, I'm HERE!!!
I live in Aspen, so here goes:
Casual all over is fine. We get a bad rep for being so POSH, but it's just a ski town like every other. Downtown Aspen eating: Takah or Kenichi for sushi, yum! Montagna for big $$ dining that is fabulous. Good bar/pub food: Bentley's, Little Annie's. Trendy: Sky Hotel bar, 39 degrees. Seafood: Pacifica....mmmm. Best BBQ for hundreds of miles: Hickory House - great breakfast spot too.
Downvalley delights: El Korita, Basalt - best Mexican around. Bistro Basalt and Tempranillo are both delicious. Breakfast MUST DO: Breakfast in America in El Jebel (kind of across from El Korita) Ella in Carbondale....and just about every restaurant in Carbondale is awesome. Carbondale is pretty awesome too.
Ok...now the important part, skiing:
Snowmass, Snowmass, Snowmass. It's got something for everyone and it's damn huge. You can spend a whole day exploring and you can find all types of terrain. Ask a local where to go on the lifts. We're friendly.
Ajax is a fun mountain too. It's pretty steep and the only downfall is the mountain flushes you back to the gondola like an airplane toilet, so try to stay high on the mountain to avoid the bottom half. The Little Nell run is usually always skied off and hard pack. Stay on the Ruthie's side and you can hit up Lift 1A.
Buttermilk....hmmm, I'm biased. I never go to Buttermilk. I know the Tiehack area is fun for some - but it's just not my type of terrain. Buttermilk is known for their terrain parks and beginner's areas. So if "bro-brah" snowboarders and little kids aren't your thing...avoid Buttermilk.
Highlands - Highlands has great intermediate terrain, however, is known for the sick stuff. Great bumps under the Cloud 9 lift. Great Apres at ZG Grill. A really fun experience if you want to get down with the local crowd.
So I'd say - 1 day each at every place but Buttermilk to get the best experience.
Shoot me a PM if you want more info!!! When are you coming?