Northwest is one of the nicer areas of D.C. with many upper class communities within its boundaries. The Naval Observatory (official home of the Vice-President) and National Cathedral are tucked away here among quaint residential neighborhoods. Enjoy a quiet retreat exploring archeological and natural history in one of the nation's oldest federal parks — Rock Creek Park.
Glover Park and Cleveland Park are your best bets in terms of restaurants and nightlife. Centered along Wisconsin and Connecticut Avenues, respectively, these Upper Northwest neighborhoods offer excellent choices for nearly every appetite. The National Zoo is situated on the outskirts of Cleveland Park. Aside its obvious appeal to children of all ages, the Zoo offers interesting events for adults as well (Brew at the Zoo, Grapes with the Apes). Comet Ping Pong is a fun venue for kids and adults alike, offering pizza, ping pong, and live music from local bands.
On the border of Washington and Maryland is the Friendship Heights neighborhood, which is home to many high-end department stores. If you wander up Wisconsin Avenue into neighboring Chevy Chase, Maryland, you'll come across the Washington area's own version of Rodeo Drive, with high-end boutiques (think Louis Vuitton, Gucci, Jimmy Choo) lining the streets.