17. Grand Canyon National Park, AZ

The Grand Canyon is awe-inspiring. Too many tourists prevent this park from taking a higher spot on this list, but remember that so many people visit this place for a reason. Take your time driving throughout the entire park and get out of the car as much as possible to see the views, smell the scents, and take everything in. Hike some of the many trails varying in degrees of difficulty and make sure to carry lots of water and food. The sun will drain your energy more quickly than you think, and remember that you have to climb back up any slopes that you walk down. In order to see more, you may want to go horseback riding through some areas on an organized tour. For the more adventurous, go rafting down the Colorado River that rushes by below (slowly carving out new features).There are plenty of places to sit down and eat for every price level and taste along the way. As it is at most national parks, the dining area offers you a chance to chat with other travelers. The best way to get more ideas is to talk with other people, and most of the people here seem to love a good conversation.As the National Park Service tells us, "this canyon is a gift that transcends what we experience. Its beauty and size humble us. Its timelessness provokes a comparison to our short existence." That really sums it up. It is most definitely worth a visit, and you're sure to have a "grand" time (ugh... sorry, it's all I got).