Apropos of not a whole lot, I decided to make a list of three places and/or things I would like to see in each state of the US. Why three? Well, why not - plus only two things wouldn't be enough to justify a visit. Note that none of the three things will be capitol buildings I've yet to visit, as those are a given, though I will include things in capital cities. Also, while I will number the three things, it is in no particular order. There isn't much rhyme or reason to the lists: it's three places I find noteworthy or interesting and wouldn't mind seeing in my lifetime, but it hardly constitutes a comprehensive list of things I'd want to see in a given state (well, maybe a few of the more boring ones) nor is it liable to constitute a list of things I would definitely have to see on any one visit to a state.
Alabama
1. Dauphin Island
2. Noccalula Falls Park, near Gadsden
3. First White House of the Confederacy, Montgomery
Alaska
1. Point Barrow
2. Kenai Fjords National Park3. Unalaska Island, Aleutian chain
2. Organ Pipe Cactus National Monument, south of Why
3. Meteor Crater, west of Winslow
2. Ozark National Forest
3. Pea Ridge National Military Park
2. Death Valley National Park
3. Channel Islands National Park
2. Loveland Pass, US Route 6 west of Denver
3. Hanging Lake, east of Glenwood Springs
2. Yale campus, New Haven
3. Long Island Sound lighthouses
1. Cape Henlopen State Park, near Lewes
2. Fort Christina State Park, Wilmington
3. Kilcohook Coordination Area
Florida
1. Florida Keys
2. Cape Canaveral
3. Dry Tortugas National Park
Georgia
1. Stone Mountain, east of Atlanta
2. Savannah
3. World of Coca-Cola, Atlanta
1. Pearl Harbor, Honolulu
2. 'Akaka Falls State Park, north of Hilo
3. Captain Cook Monument, south of Kailua-Kona
1. Craters of the Moon National Monument, southwest of Arco
2. Shoshone Indian Ice Caves, north of Shoshone
3. Mesa Falls, northeast of Ashton
1. Old State House, Vandalia
2. Kaskaskia (only part of Illinois west of the Mississippi)
3. Confluence of the Ohio and Mississippi Rivers, south of Cairo
1. Indiana Dunes National Lakeshore
2. Corydon (old capitol plus a Civil War battleground)
3. Turkey Run State Park
1. Field of Dreams, east of Dyersville
2. Herbert Hoover National Historic Site, West Branch
3. National Mississippi River Museum and Aquarium, Dubuque
1. Castle Rock, south of Collyer
2. Monument Rocks, south of Oakley
3. Geographic Center of the Contiguous United States, near Lebanon
1. Mammoth Cave
2. Abraham Lincoln Birthplace National Historic Site, south of Hogdenville
3. Churchill Downs, Louisville
1. Grand Isle State Park
2. Chalmette Battlefield and National Cemetery, east of New Orleans
3. Kent Plantation House, Alexandria
1. Acadia National Park
2. West Quoddy Head Lighthouse
3. Snow Falls Gorge, West Paris
1. Point Lookout State Park
2. St. Clement's Island State Park
3. Ocean City miniature golf courses
1. Cape Cod
2. Nantucket Island
3. Salmon Falls Glacial Potholes, Shelburne Falls
1. Mackinac Island
2. Isle Royale National Park
3. Sleeping Bear Dunes National Lakeshore
1. Headwaters of the Mississippi, Lake Itasca
2. Gooseberry Falls State Park
3. The Northwest Angle
Mississippi
1. Vicksburg National Military Park
2. Biloxi Lighthouse
3. Fort Massachusetts, West Ship Island
1. Gateway Arch, St. Louis
2. Confluence of the Mississippi and Missouri, north of St. Louis
3. Truman Presidential Library and Museum, Independence
1. Glacier National Park
2. Little Bighorn Battlefield National Monument, near Crow Agency
3. Missouri Headwaters State Park, near Three Forks
2. Doorly Zoo and Aquarium, Omaha
3. Great Platte River Road Archway, near Kearney
1. Lake Tahoe
2. Hoover Dam
3. Las Vegas
1. Mount Washington
2. America's Stonehenge, near Salem
3. Lost River Gorge, near North Woodstock
1. Cape May
2. Barnegat Lighthouse State Park, north of Long Beach
3. Great Falls of the Passaic, Paterson
1. White Sands National Monument, southwest of Alamogordo
2. Carlsbad Caverns National Park
3. Capulin Volcano National Monument, southeast of Raton
1. Niagara Falls
2. Boldt Castle, near Alexandria Bay
3. Montauk Point
1. Kitty Hawk
2. Cape Hatteras
3. Linville Falls, Blue Ridge Mountains
1. Geographic Center of North America monument, Rugby
2. International Peace Garden, north of Dunseith
3. Sheyenne River Valley Scenic Byway, southwest of Fargo
1. Put-in-Bay (on South Bass Island in Lake Erie)
2. Cuyahoga Valley National Park
3. Grant Birthplace, Point Pleasant
1. Ouachita Mountains, south of Poteau
2. Natural Falls State Park, west of Moseley
3. Lake Texoma State Park, southwest of Durant
1. Crater Lake, northeast of Medford
2. Ice caves, south of Bend
3. Hells Canyon Overlook, north of Homestead
1. Fallingwater, Mill Run
2. National Aviary, Pittsburgh
3. Flight 93 National Memorial, north of Shanksville
1. Newport
2. Block Island
3. Fort Adams State Park, near Newport
1. Charleston
2. Myrtle Beach (mini golf capital of the world!)
3. Congaree National Park
1. Mount Rushmore
2. Wind Cave National Park
3. Geographic center of the 50 states, near Castle Rock
1. Great Smoky Mountains National Park
2. Rhea County Courthouse and Scopes Trial Museum, Dayton
3. Shiloh National Military Park
1. South Padre Island
2. San Jacinto Battleground State Historic Park, east of Houston
3. Guadalupe Mountains National Park
1. Zion National Park
2. Capitol Reef National Park
3. Arches National Park
1. Lake Champlain
2. Chester A. Arthur State Historic Site, east of St. Albans
3. Ben & Jerry's Ice Cream factory, near Waterbury
1. Mount Vernon
2. Shenandoah National Park
3. Fredericksburg and Spotsylvania National Military Park
1. Point Roberts
2. Olympic National Park
3. Mount Rainier National Park
1. Weirton
2. New River Gorge
3. Falls of Hills Creek Scenic Area, southeast of Richwood
1. Door County
2. Apostle Islands National Lakeshore
3. Amnicon Falls State Park, southeast of Superior
1. Yellowstone National Park
2. Grand Teton National Park
3. Devils Tower, northeast of Gillette
Feel free to weigh in on any you've seen, or suggest alternates. Do remember that if I haven't listed something really obvious (like the Grand Canyon) it's probably because I've already been there, although me completely overlooking something can't be totally ruled out.