There are 15 official trails leading into the canyon. If you plan on spending the night you're going to need to plan well ahead of time in order to secure your backcountry permit. The park only issues 13,000 permits against 30,000 requests each year [source: NPS.gov]. For solitude, try out the North Rim - this gets about 10 percent the number of visitors as the more familiar South Rim.
7. Yosemite National Park
Most any of America's national parks are gorgeous, but California's Yosemite may take the cake as the most spectacular. Occupying 747,956 acres (or 3,027 square kilometers), the park is roughly the same size as the state of Rhode Island and has 800 miles (1,287 kilometers) of hiking trails - enough to satisfy the most ardent enthusiast [source: NPS.gov]. More than 3.5 million people visit the park each year, and there are more than 15,000 backcountry permits issued each year for overnight backpackers.
When it comes to choosing what part of the park to explore by foot, don't get too picky. With dozens of trails that cover those 800 miles, you're sure to have a fulfilling experience wherever you go. In planning your hike, visit the National Parks Service Web site to check out the areas you might like to try. There are dense forests, glacier-formed mountains, lakes, rivers and no shortage of wildlife. The peaks of El Capitan and the grandeur of the giant sequoia trees are not to be missed.