I liked the underground tour. I was expecting a little more to it; it seemed like they took a 45 minute tour and stretched it into 2 hours. However it was still worth doing once.
I really enjoyed the
Museum of Flight I'm not sure if we just hit a good day, but they had a former Shuttle astronaut explaining the ISS replica/exhibit and how everything worked. Nice to have a guy who actually went into space telling you how everything worked.