I know about the monuments & Smithsonian (lived in the area as a kid a couple years & then visited about 17yrs ago) but I know things have changed.
We will be staying at a Marriot nearby - got that booked.
Will be taking the kids 12, 7 & 4
Any tours, things to do - it will be a quickish trip on a budget

we'll be there 3 or 4 days.
And if you have any restuarant suggestions - I'm thinking we'll do like when I was a kid & take a backpack with pb&j for picnic lunches on the mall & then we'll catch a meal somewhere for supper once everything is closed for the evening. b'fast is that the hotel for free - YAY!