Illinois means Chicago for most visiting families, and the city earns that top billing. The skyline is the first thrill: the Skydeck at Willis Tower and 360 Chicago both put kids on a ledge over the Loop, and an architecture boat tour along the Chicago River explains the skyscrapers in a way that actually holds a child's attention. Navy Pier anchors the lakefront with a Ferris wheel, a children's museum, and fireworks in summer, while Millennium Park gives everyone the mirrored Bean to pose in front of and, come winter, an ice rink right downtown.

The museums do a lot of the heavy lifting on a family trip here. The Field Museum has SUE, the largest and most complete T. rex skeleton ever found, the Shedd Aquarium puts kids face to face with beluga whales, and the Museum of Science and Industry runs a real submarine tour alongside its hands-on exhibits. Lake Michigan itself supplies a proper beach day at Oak Street Beach, a short walk from downtown, and deep-dish pizza and Chicago-style hot dogs handle dinner without complaint from anyone at the table. Beyond the city, the Illinois prairie opens up with state parks, river towns, and Route 66's opening stretch for families who want a road trip attached to their city break. The accommodation runs from grand downtown hotels with skyline views to family-friendly suites near the museum campus, many with pools and easy access to the Magnificent Mile. Illinois is the compact, walkable big-city option, one great city doing an unusual amount of the work.