I'm a huge fan of the Philadelphia-based design studio The Heads of State, run by Dustin Summers and Jason Kernevich. Their awesome work is no stranger to Double Takes.
Summers and Kernevich's equally awesome side project Pilot and Captain honors "the good old days of planes, trains, and discovery" with city-specific posters and t-shirts. Their flagship series of t-shirts feature an assortment of cities with the local airport code. The designs are original and printed on cotton.