Washington.org is the official tourism site for Washington, DC and includes everything: attractions, things to do, restaurants, hotels, events, and maps. They also have a great list of 100 Free (& Almost Free) Things to Do in Washington DC.
The Washington Post’s Going out Guide is a great source for nightlife, festivals, music, movies, dinning, and other event. You can search through their calendar or sign up for their newsletter to get emails twice a week a bout what to do and where to go in the Washington area.
National Harbor is a 350-acre resort destination that includes the Gaylord National Resort and Convention Center, Tanger Outlets, thousands of hotel rooms, hundreds of residential and office units, tree-lined promenades with scores of popular shops and restaurants, a marina, Additionally, MGM Resorts International is currently building a $1.3 billion integrated casino resort complex on 23 acres overlooking the Potomac River with a 23-story, 300-plus rooms and suites hotel.
National Harbor offers restaurants, shopping, entertainment, and homes within steps of the Potomac River. The expansive waterfront with its marinas and piers, designed to accommodate concerts, dinner cruises, and other signature events, also offers a water-taxi service on the Potomac to Georgetown and Alexandria, Va. National Harbor also has a 180-foot observation wheel – the Capital Wheel –featuring panoramic views of the nation’s capital.