DJ’s Clam Shack sits unassumingly on Duval Street, the beating heart of Key West’s famous strip, looking like it was plucked straight from a New England coastline and dropped into tropical paradise.

Sno-White Drive-In stands as a delicious time capsule in California’s Central Valley, where the burgers are still juicy, the shakes are still hand-spun, and your wallet doesn’t leave crying. In an age ...