Given the crowds, I decided to forgo more embassy visits in favor of finally seeing the Frogs! exhibit at the National Geographic Museum (which is at 17th and M, so near the end of the route). It was worth a look. There were Vietnamese frogs that look like patches of moss, for example. The highlight was, of course, the poison dart frogs which are just beautiful, like living jewels.
All in all, it was a very pleasant day. I'm looking forward to doing the walk in two weeks that involves open houses at various other embassies. That walk focuses on South America, but there are also open houses at the embassies of Madagascar and Micronesia among others.