Glacier NP. The road to the sun is beautiful. Grand canyon. MT Rushmore in the black hills and nearby is Crazy Horse memorial park. Garden of the Gods. Those are some of the favs I have visited.
Mammoth Cave, Kentucky Washington D.C. (a must for every American) Carlsbad Caverns National Park, New Mexico (at sunset millions bats exit the cave in search of mosquitos and other flying insects - it is a sight to behold) Big Sur, California (spectacular) Ashfall Fossil Beds Historical Park, Nebraska (little known but absolutely fascinating) Grand Canyon National Park, Arizona (you can take the ultimate selfie) Roswell NM (not much there but when I went in 1997 they were celebrating the 50th anniversary of the UFO crash) Las Vegas, NV (hey Sin City) New York City (Sights, sounds, locales, too numerous to mention) Hotwater
New Orleans and Nashville would be on my list where it comes to towns, among several other natural and cultural sights on the southern half of the US. Hey, I'm a tourist and not american. I might have different priorities I'd probably rather spend a few days in Miami than in Washington DC. When in New york I would rather walk the streets of the Bronx and Brooklyn then go to some art museum, central park or Times square. Although the northern half (im dividing it very roughly here) has beautiful and extensive nature and lots of cool culture stuff too of course, I am pretty sure I'd go on 2 trips in order to go there: my first and maybe only trip would focus on driving through the southern half, from let's say New Orleans to Los Angeles. One of my dream trips.
Starting in Maine, Arcadia National Park highest point on the east coast. Mt Washington, New Hampshire, noted for killing people. 6,288 ft and some of the most violent weather in the world. Highest recorded non cyclone wind in the world at 231 miles an hour, tundra climate. 150 people have died on the mountain, mostly from exposure. It also has a cog railroad that takes you to the top, 1 hour trip for 3 miles. Cherry Springs State Park, PA. Some of the darkest nights on the East coast. It has a dark sky park with electric outlets for tracking telescopes, it's a 2 on the Bortle Dark-Sky Scale. Niagara Falls, NY. Can't miss that. Meadowcroft Rockshelter, PA. Oldest continuously occupied site in the New World. Over 19,000 years old. Great Serpent Mound, Ohio. Largest serpent mound in the world, 130 CE. Skyline Drive, Virginia; BlueRidge Parkway (longest park in the U.S 469 miles): Great Smokey Mountains, Tennessee North Carolina. Experience the bottom of the Appalachian Mountains, one of the oldest ranges in the world, born 680 million years ago. Cape Hatteras, North Carolina. The graveyard of the Atlantic. It used to be a quaint seaside town accessible only by an hours long drive down a two lane Outer Banks road swept by sand and wind or by ferry. North of here is the Wright Brothers memorial, they choose the island for its winds and isolation. Okefenokee Swap and the Everglades, Georgia and Flordia. Two of the largest swamps in the world. There's a neat one lane dirt road on the north that parallels the Everglades. I believe it's about 20 miles long and you can stop and stand next to wild alligators, swap birds, etc. That's all I have time for now....