San Francisco

San Francisco

San Francisco is hills, fog, Mission burritos the size of forearms, and pastel Victorians stacked like dominoes. Karl the Fog has his own Instagram, the cable cars are still mechanically pulled by cables running under the street, and the Pacific shows up at the end of every west-bound avenue. The food is wildly good, the views are theatrical, and yes, you'll get cardio just walking to the corner store.

Huntsville

Huntsville is Rocket City, with NASA's Marshall Space Flight Center, the Saturn V rocket on display at the Space and Rocket Center, and a tech and engineering economy that punches way above the city's size. Cummings Research Park is the second-largest research park in the U.S. The Tennessee River and Monte Sano State Park give it a quiet outdoor side. Affordable and surprisingly smart.