When I was in 5th grade (I think?) we went to the nation's capitol as a field trip. My mom volunteered to be a chaperone, as a result over the following years, we would go back. We would go into every museum, if you get a room at the right hotel (I forget which one we stayed at back to back) you can walk to any and all the museums, you can spend all day in several different museums. I highly recommend anyone to take such a trip if you've never been to DC. The city is full of so much history that we all have been taught, its something else to see it in person.