Go to the Spy museum. Kids love that.
Personally I found the spy museum - most of it anyway - to be a bit more geared towards grown-ups. LOTS of reading, lots of folks standing impatiently behind you for their turn, LOL. SO, although I thought I would love it, I felt it was over crowded, dull and a little over priced.
Now, we went down to the house where Lincoln was taken after being shot, and later died. I think it is about two blocks from the Spy Museum, anyway - we did enjoy that.