Washington DC is amazing! You will want to see THE WHITE HOUSE, of course; even if you can't get in on a tour it is worth seeing from the street. Lincoln's Memorial is very impressive, especially at night. The Smithsonian is somewhere I visit every time I go; I plan a full day there and still just have barely enough time for the highlights in each of the different museums which interest me. The National Cathedral is a definite must-see. You will want to witness our government in action while you are there if at all possible; contact your congressman prior to your trip to see if he or she can set you up with any special tours. The Library of Congress is another must-see. Take comfortable shoes, cool clothing, a good umbrella, and drink lots of water. Have an amazing time!!!
Washington DC is much like most major US cities; great night life, great people, lots of places to visit, and downright nasty weather when it decides to. Springtime is beautiful with mid to upper 70s during the day, and 60s at night.
Oh my goodness!!! I LOVED DC I went in October when the trees were changing (and it snowed AWESOME I'd never seen snow before being a FL girl and all lol) Lincoln Memorial (they ripped up the reflecting pool for renovations when we were there :( ) MLK memorial which was pretty cool, we got a tour of the white house (it was cool but there were only about 5-6 rooms I'd do it again if I could though), Tomb of the Unknown Soldiers, The Smithsonian, see how US currency is made (smells like paint when your taking the tour and unfortunately they don't give samples lol) the list is endless we went 10/11 and I want to go back sooooo bad we missed so much and we were there nearly 2 weeks I think.