Well I found the cafe I was looking for yesterday...I just stumbled upon it now after deciding I needed a break from DC riding for a while.
The spy museum was fun. I got out around 4, by then I was too exhausted to see another museum. Just as well, it turned out, because there's no parking by the Holocaust museum, and I was too tired to park far away and walk. Then I got on the freeway by accident - it was that or cut across 4 lanes of angry traffic. It took several miles of highway driving to get back into the city, where I found myself back on M Street, near Georgetown. I drove a few blocks, decided to pull over and see what I saw, and presto! - there was a French cafe right in front of me.
A little too cafe-ish, though, because the seats upstairs are little cushion chairs with no backs, a few inches below round wood tables, so it's quite uncomfortable to use a laptop on them. (I've been carrying a pretty heavy backpack around all day so my spine needed a rest.) Luckily there was one big wood table which I found a seat at, along with two other people doing the same.
I don't think I like DC very much. I look forward to leaving tomorrow morning, hopefully to a campsite between here and Illinois.