By day, this forested hot spring just north of Steamboat Springs teems with families splashing in the all-natural pools. After dark, it becomes exclusively adults-only — and clothing-optional; don’t be surprised if you spy a cowboy or two taking a dip au naturel. Secluded hillside cabins and train cabooses are within sprinting distance from the pools, for those cooler Colorado nights.

The Experience: Denver is the perfect urban adventure for anyone who likes midsize cities. It's easy to navigate and manage and doesn't feel at all claustrophobic, but offers endless cultural excursions, gourmet dining experiences, and a fun nightlife you'd expect from large cities. Make sure you visit the Denver Art Museum, check out the breweries in the RiNo neighborhood, and stay at the Crawford Hotel, which is in the old Denver Union Station. For a boutique hotel, stay at The Maven Hotel.