Arapahoe Basin is a small, exceptionally high ski area near Keystone with excellent snowfall record, tending to be among the first resorts to open and last to close each season.
Commonly referred to as A-Basin, especially by locals it has a reputation for gnarly terrain, and a relatively rowdy atmosphere, including plenty of BBQs and boozing in spring skiing time, a noticable contrast to the increasingly commercialized resorts in Colorado.
Lifts provide access to good mix of open and wooded runs of every standard, plus serious steeps (some reached by hiking - including the legendary East Wall). The resort almost doubled in size with the opening of Montezuma Bowl and a fast quad (adding 400 acres and 34 runs). It now has a mid-mountain restaurant too. There is no on site accommodation, though there is plenty at nearby Keystone, 8km away.