We'll be 4 adults going and since we've never been we have no idea as to where we will/should stay. Info is appreciated!
Here is my list of must do's (keep in mind I have 2 kids but have been both with and without). We have been a few times in the past 2 years - DH has work down there.
Tour of Capitol Building - you may be able to book on-line through your Congressman (here is my congressman's website
http://www.house.gov/pitts/tour_request.shtml) I am not sure if all congressmen handle this the same way. You should at least be able to get the contact information at
www.house.gov/last name of your congressman. This is also where you can book a tour of the White House. Our family has not yet been successful with this, even booking 6 months out - hopefully this year.
Bureau of Engraving & Printing - tickets are free but required as the tours are timed
www.moneyfactory.gov/
Washington Monument - again free but tickets required. You can book them in advance but there is a service charge
http://www.recreation.gov/tourParkDetail.do?contractCode=NRSO&parkId=77811
Another great view is the Old Post Office Tower
http://www.nps.gov/opot/index.htm. It is free and the 3rd highest point in DC. It has an interesting history too. The rest of the Old Post Office is basically a food court which we did not care for.
Smithsonians - our favorites are American Indian (great cafeteria too), Natural History, American History, Air & Space & Zoo. We really want to get to Udvar-Hazy which is part of Air & Space but it is in VA and requires a few different modes of public transportation to get there. We recently wandered into the Portrait Gallery/American Art and want to spend more time there.
National Archives - the Declaration of Independence & Constitution are fading fast - I feel they are a "must see". There is a park across the street with really neat sculptures but the name is escaping me right now.
Holocaust Museum - tickets are free but required for the main exhibit.
We were there for a couple of days last week and went to the Botanical Gardens - nice but would not say a must see and Madame Tussauds. My kids had really wanted to go and really enjoyed it but even with discount tickets, I thought it was over priced.
We also really enjoyed the Old Town Trolley Tours. We did both the inner (dowtown) and outer (National Cathedral, Georgetown, Embassy Row). We also did the Monuments by Moonlight Tour and thoroughly enjoyed that. We did not like the DC Ducks - not sure if it was just our tour operator or the tour itself. We loved the Ducks in Baltimore & Philly.
I am interested to hear from others for other to see, we always visit our favorites but like to try something new also.