Like the life cycle of the North American mayfly, summers in Sun Valley are short and never-resting. For starters, the nearly million acres of Sawtooth Wilderness and 40 peaks above 10,000 feet provide opportunities no matter in which direction of the compass you dart. World-class trout waters such as the Big Wood River, Silver Creek and Copper Basin were able to keep master fisherman Ernest Hemingway away from his typewriter. Then there's horseback riding through aspen groves, whitewater rafting on the Salmon or playing a few rounds at the Robert Trent Jones Jr.-designed Sun Valley Golf Course. Savvy mountain bikers take the lift to the 9,000-foot summit of Bald Mountain and let gravity do the rest. Family riders will find 30 miles of paved trails. Outfitters offer climbing, hiking and backpacking adventures. Or let a llama do the heavy lifting on a picnic hike. Nearby Ketchum is Aspen without the attitude: There are enough restaurants and bars to keep King Henry VII happy, but without being royally screwed by the tab. Don't leave without taking in the Saturday evening outdoor ice show at the Sun Valley Lodge or sipping a Manhattan in the Rat-Packesque Duchin Lounge. Sun Valley is conveniently tucked into the western edge of the Mountain Time Zone, so days stay bright until 9:45 p.m. or so. When you're a mayfly, every minute counts.
•DON'T MISS Hike nearby Proctor Mountain, above Trail Creek Cabin, the birthplace of skiing in Sun Valley, to see the world's first chairlift. Proctor is one of the first hills to shed its snow in spring, so its trails are popular with locals recovering from cabin fever.
•BEST DEAL Two nights' lodging in Sun Valley and a half-day of rafting costs $138 per person, double occupancy. 800-634-3347; visitsunvalley.com