DCist's put out a call for the quintessential movie about Washington, DC inspired by this map, and I'm intrigued both by Aaron Morrissey's suggestions, and by what people are tossing out in comments. Most of the great movies set in Washington either have the city as an incidental setting—Wedding Crashers makes some minor use of the fact that some of its characters are in the administration, for example. Or they're about the city's most nationally prominent industries: lobbying, government, politics, or the military and intelligence communities.
There's absolutely nothing wrong with that. Movies like the utterly fantastic Breach, which as commenter apz said, "focuses on mid-level government officials and their day-to-day work, one aspect of DC that's rarely dramatized," absolutely capture an authentic part of Washington.
But there aren't as many movies that are about native Washingtonians rather than transplants who come to town to work in one of those big industries, that are as ordinary, authentic, and local as Fast Times at Ridgemont High is to California or as Groundhog Day is to Pennsylvania. The best recent candidate, I think, is a movie that was unfortunately overlooked by both audiences and awards when it came out, Kasi Lemmons' terrific 2007 flick Talk to Me:
The movie's a biopic of WOL-1450's Petey Greene. Greene was born in Kentucky, but grew up in Washington, dropped out of Cardozo Senior High School, served time for armed robbery, and left prison to a job as a DJ. He did radio and television work until 1982 and won two Emmys (he also helped launch Howard Stern's career by giving him one of his first TV appearances, but I'll leave y'all to judge that part of his legacy). He was also a long-time prison reform activist.
Don Cheadle is fantastic as Greene, but the movie's more than biography. At a time when U Street is one of the hottest neighborhoods in the city, Talk to Me is a story about the riots that make the district's recovery and vibrancy so important. And the movie's about someone choosing to stay in Washington, DC rather than making the leap to the national entertainment circuit. It may not have the iconic status that something like The Exorcist or All the President's Men do. But if folks outside of DC want to know more about the city's heart, it's well worth watching.