I didn't just eat a lot of food, I swear I did other stuff!
I visited the Smithsonian Museums on the National Mall, in particular Air and Space, American History, and Natural History. Air and Space was pretty cool, I stuck mostly on the space side, of course I looked around at all the stuff in the milestones in flight gallery, which was pretty awesome. The rocketry gallery was pretty cool. One of the coolest things was the V-2 rocket.
They obviously can't have too much of the big space stuff, since it is a relatively small building, compared to, say, the Kennedy Space Center, but they do have some cool models like a walk-through of Sky Lab, and some cool artifacts, like moon tools!
I also had a good time at the Natural History Museum, I visited that a couple times. I loved the gem collections, it's the most comprehensive one I've seen. To me it even beats AMNH in New York. I saw the Hope Diamond, of course. They have a few really great set pieces, but above all just awesome specimen after awesome specimen. Here's a close-up of a really great copper sheet, and a "steam-boat" tourmaline:
You can't tell from the pictures, but that copper sheet was about 7 by 4 feet, and the elbaite piece is about a foot tall. Pretty sweet. I spent some time in the ocean halls, too. They have a giant squid in a case that sort of reminds me of a Damien Hirst piece. I actually liked the new displays they've put up. They tend to have a few example specimens with a brief description, and some points of comparison to look at specifically. It's simple and appealing, but actually gives you something to think about.
They have an exhibit on there about forensic anthropology, which begins by covering technique info, modern day tools and the like, showing you examples of various identification techniques. The later, larger half is of Jamestown finds, and describes the lives of the people through piecing together the bone evidence and other historic evidence. That was a pretty great exhibit, both parts were quite interesting. And they've placed it in a very apt spot in the museum, between the halls of animal bones and human historic bones. On the way to the exhibit, Anna and I looked at the vestigial leg bones of various animals, from boas to whales. We also went down to the ice-age mammals hall of bones!