At the heart of the Rocky Mountain National Park is the 45-mile Trail Ridge Road, open from late spring to mid-autumn, when snow forces its closure. Traverse it by car from Estes Park (made famous by the film "The Shining") to Grand Lake, or get out of the car to explore the 265,000 acres on foot, bike and horseback or, in winter, by snowshoe and ski. With more than 350 miles of trails, pick an easy day hike or a strenuous day's hike that requires backpacking. You can also camp out, fish (mostly catch-and-release) or rock- climb.