When we're in Sun Valley in the winter, we ski on Baldy, or cross country ski on the Sun Valley lodge golf course - stopping for lunch at the Trail Creek cabin. Or, snowshoe, cross country ski on the hundreds of groomed trails just north of town. We snowmobile at Smiley Creek - just over the Galena summit. And, of course, dine out! Favorites for lunch: Apples at the base of Warm Springs during ski season, The Wine Shop, Perry's, or Cristina's for brunch, and of course the Pioneer Saloon for steak, Il Naso for Italian, Globus for Asian fusion, La Cabanita for authentic Mexican. The Ketchum Grill, The Sawtooth and Village Square Tavern all serve continental/American fare. My most favorite is Enoteca on the corner of Main and Sun Valley Road. They have wood fired pizza, extensive wines, gourmet dinners, friendly waiters and they honor reservations - although hard to get.
In summer, hiking or biking rule! There's a 17 mile gravel bike path between Galena Summit and Ketchum. After that a paved 18 mile path from Ketchum to Bellevue. Or, the paved 10 mile loop through Sun Valley village and Elkhorn. One can also hike up Baldy, have a bite to eat on top and take the chair lift down (free to those who make it to the top on foot). Outside of town, the Sawtooth mountains offer thousands of day hiking trails. Red Fish Lake is a great place to hang for the day, with a beach and paddle boats for hire.