For lighter stuff, the Internatonal Spy Museum was great honestly. And if you want a little laugh, the Darth Vader grotesque on the Washington National Cathedral is a wild thing to see. It's reeeeally high up, but it's an approved gargoyle lol I cherish that silly memory

The Tomb of the Unknown Soldier; The changing of the guard there is what I remember most. The Vietnam Memorial was also nice--I found some names from my family there. It's solemn stuff, but makes the events more tangible and has visit value. Taking the metro too; which should take you close to both.

Admittedly learning this app still, but we out here, fresh off the presses