Vacation to Washington DC next weekend. We have already done the main tourist stuff. What to do now?

We (Mom, Dad, 21 year old brother, husband and I) are going to DC next weekend. We have already done the main tourist things (WA monument, wall, science musem) Anyone have any other suggustions? My family likes history, food, and fun... I'll check this tomorrow and pick my best answer before we leave. Thanks.