Big Sky/Moonlight Basin was created for the guy who can go all day. Here, you can ski until your heart’s content and you’ll never get bored—and rarely have to take the same run twice. It’s the largest ski and snowboard resort in the United States, with 5,750 acres of ridable terrain, 4,400 vertical feet, and more than 250 runs. Plus, you can access dozens of miles of Nordic ski trails to get in a good cardio workout. The entrance to West Yellowstone is a short drive away so you can mix in snowshoeing and hiking: the ultimate playground for endurance athletes.