The Museum of Flight has an M-21 - in the Blackbird family but a few feet shorter than the SR-71. It's a truly wonderful plane and I love that you can walk underneath it and get right up close. As I recall they also have one of the engines pulled out to look at as well.

The Museum of Flight also has an entire SR-71 cockpit (salvaged from a crash) that visitors can sit in. It's the only place I know of in the world where regular people are encouraged to touch one.