Going to DC with a friend for a couple days and am wondering if Hexbear has some ideas on what to do. We already have a list of the 4 (maybe 5) museums we're going to, so probably don't need any suggestions there. (Though feel free if somewhere was super cool to you.) Preferably things close to metro and/or downtown.
If you go tour around Georgetown (it's a nice area) try also going down the Exorcist stairs. Near Georgetown there's a great ice cream shop I'd recommend called Thomas Sweet. It often has a line out the door. I'd prioritize any of the great free museums over this, but there you have it.
It'll be warm enough to justify carrying canteens or bottles of water around with you, so don't neglect that.