3. Yellowstone National Park
America's national parks are some of our greatest resources, and most beautiful and affordable travel spots. Float on the scenic Snake River, watch the wildlife, stroll along the easy boardwalk trails in Norris Basin or  grab a bite to eat at the historic Old Faithful Inn.

(Bonus tip: if you're a US citizen 62 or older, you can buy a Senior Pass for fee-free access to 118 National Park Service sites and 2,000+ additional recreation sites. Plus, three traveling companions can join you! An annual pass costs $20, and a lifetime pass costs $80.)