Would live on the beach and vacation in the mountains. Love skiing and think I would love mountain biking but I wouldn't be someone that would do them everyday. Ideally, I would live on the beach in northern California and have a lake/mountain house on Lake Tahoe that I could spend my weekends at.
On another note... think lake activities are very underrated which is why I think my scenario is the best. Jetskiing, waterskiing, etc. are all totally awesome/cool/sexy things to do.