Florida Keys vs Washington DC

The Florida Keys are America's most famous road trip island chain, a necklace of coral islands linked by the Overseas Highway as it hops 113 miles from Key Largo to Key West over 42 bridges and turquoise water. Starting from Miami, you can be snorkeling North America's only living coral barrier reef at John Pennekamp Coral Reef State Park within a couple of hours. Farther south, Islamorada is the sportfishing capital with tarpon feeding at the docks, Marathon has a sea turtle hospital and the soaring Seven Mile Bridge, and Bahia Honda State Park offers some of the best natural beaches in the Keys. The road ends in Key West, a colorful, easygoing town of conch houses, Hemingway's cats, and the nightly sunset celebration at Mallory Square. This plan covers the full Key Largo to Key West run in four days, then adds a day trip by ferry or seaplane to remote Dry Tortugas National Park and its giant brick fort. Navigate by the green mile markers, slow down in Key deer zones, eat plenty of fresh fish and key lime pie, and book Key West hotels early in winter.

Washington DC may be the best family city in America, mostly because so much of it is free. In three days with kids you can stand under real spacecraft at the National Air and Space Museum, meet the Hope Diamond and towering dinosaur skeletons at the National Museum of Natural History, and see the original Star-Spangled Banner at the National Museum of American History, all without paying admission. Some sites use free timed-entry passes, so reserve them before you go. Between museums, let kids run on the grassy National Mall, ride the carousel and picnic with food-truck lunches. Save an evening for the monuments at sunset, when the Lincoln Memorial glows, the Reflecting Pool mirrors the Washington Monument and the crowds thin out. The Metro makes getting around easy, and younger children ride free with a paying adult. With more time, see giant pandas, elephants and great apes at the free National Zoo, tour the US Capitol and the stunning Library of Congress, crack codes at the International Spy Museum, and day-trip to George Washington's Mount Vernon and the brick sidewalks of Old Town Alexandria. Spring and fall are ideal, with cherry blossoms in late March to early April.