First time visiting Washington, DC

The National Archives & Records is a must see for any visitor. You can book a timed spot in advanced and that is highly recommended. United States Capitolis also an important building to see. Contact your Representative to obtain tickets. There are many museums that are a part of the Smithsonian. The Museum of Natural History is wonderful and the Hope Diamond is a must see. For modern art visit the sculpture gardens at the National Gallery of Art and Hirshhorn Museum and Sculpture Garden. Away from the Mall, the Washington National Cathedral (moon rock stained glass window and Helen Keller burial site), Steven F. Udvar-Hazy Center (space shuttle and Enola Gay) and the National Zoo Dr NW(panda bears) are all wonderful places to see on a first visit.  The amount of time you have, the availability of transportation and the ages and interests of the people in your group will help you decide. 

All of the monuments (1); Smithsonian museums -- any flavor (2); Mt Vernon in Alexandria VA (3), International Spy Museum (4) Newseum 

my number one suggestion to anyone headed to dc is always the United States Holocaust Memorial Museum - it is incredibly well done and definitely a must do.  on a lighter note, my wife and i did the Newseum  a couple of months ago when we were there and really enjoyed it, lots and lots to see - some cool exibits.

be sure to take some time to walk the National Mall depending on how much time you give you can see ww2, vietnam, lincoln, washington, capitol building if you go from one end to the other - its a great walk on a pretty day.

of course the Smithsonian is one of the best in the world and definitely worth some time.

if you head to the whitehouse make sure to go right down the street to the The Willard and have a drink in the hotel bar - awesome place and usually pretty good people watching there.

DC offers diverse alluring attractions in it. Yeah it is famous among tourists for it's historical spots that makes it more prominent one among others. But there is lot of spots for having great trip. If you are a nature lover then Great Falls National Park, Hillwood Museum and Gardens, Kenilworth Aquatic Gardens and Lincoln Park are must to see attraction for you there. If you are a history lover then it offers several remarkable memorials in downtown. Monuments and Museums as well. National Air and Space Museum and Museum of Natural History  and many others. I am a huge fan of nature's and history's charm so i had explored all these attractions during my tour http://www.getbustours.com/3day-boston-washington-baltimore-philly-york-tour.html.

I love the Newseum.  I would plan to spend for at least several hours there.

Definitely the The White House