I recently took a trip to Washington, D.C., which I've wanted to visit since high school when I was considering a career in government. When my friend invited me to join her on a visit to D.C., I jumped at the chance.
On our first full day in D.C., we visited:
U.S. Capitol
Library of Congress (my favorite attraction)
Supreme Court
You can sign up for a tour of any of these attractions through your Congress person. However, tours to the general public are also available without a prior reservation. Just check the site's website for tour info.