You'll never forget the world's first national park, because this nearly 3,500-square-mile area of bucolic splendor is full of unique natural wonders including colorful hot springs, gurgling mudpots, fumaroles, dramatic canyons and waterfalls, wandering bison herds, and exploding geysers. Eat lunch at the Old Faithful Lodge while admiring the classic parkitecture and waiting for Old Faithful to spew. You can also hike, fish, horseback ride, take a photography class, step on the Continental Divide, take a selfie under Roosevelt Arch, snowshoe, visit the museum dedicated to the guys and gals in olive green and beige, or just meditate by a peaceful lake. It is further afield than Grand Tetons but certainly still within day-trip range if you don't want to uproot your base camp in Jackson.