It depends on what you want to do.

There are Michelin-starred and other very good restaurants, but almost all are downtown  and none are in the Tysons area which mostly has chains ranging from McDonalds up to Capital Grille that you can find in any big city.. The very good and creative  Jose Andres restaurants are mostly clustered near the Gallery Place Metro stop. Google "Think Food Group" to get links to them all; China Chilcano and Oyamel are my favorites.  Tysons is a big area, but it has three Silver Line Metro stops that can get you downtown. Even if you have a car with you, the Metro will be easier than driving (and cheaper too considering parking)

There are the Smithsonian Museums and the National Gallery of Art museums of course, mostly lining the Mall. One partial exception is the National Air and Space Museum's Udvar-Hazy annex which is close to Dulles if you are flying in or out of there.  They have a space shuttle, a Concorde, and a SR-71 Blackbird among other things. The main Air and Space Museum is downtown on the south side of the Mall, but aircraft and spacecraft are big, and they use the Udvar-Hazy Center for some of their larger exhibits. There is a county bus line that starts at Dulles and the Udvar-Hazy Center is one stop away (see link for information about the museum and the bus from Dulles). You can get to the airport a few hours earlier than you need to for your flight, check your luggage, and take the bus to the museum.