If you are only going to visit one location, or if you have young kids, or you want to hit up the other smithsonian museum's the Air and Space museum on the mal

If you are only going to visit one location, or if you have young kids, or you want to hit up the other smithsonian museum's the Air and Space museum on the mall takes priority. That said, I've been to the Air and Space museum a handful of times, and I only go back when I have visitors in town who want to do the tourist thing. The udvar-hazy faculty is something I'll visit on my own over and over again. It's an incredible collection of important machines including the discovery space shuttle, an SR71 blackbird, the Enola Gay, etc.