If I had to do only one, I would do the new air & space museum annex, since I have not yet seen it, and I have seen all of the mall museums. My job is in the field of historical research, and I LOVE the history museum, so if there was no new museum, I would go there. I found the main Air & Space museum a little disappointing. I guess I found a lot of the exhibits to be focusing on the interest level of a younger crowd than me. There was a lot of OH, WOW stuff there to look a briefly, but not a lot to ponder -- and it was too noisy and too crowded. In other words, I learned a lot more about the Wright Brothers and the construction of their first airplanes by watching the recent PBS documentary than I did by actually seeing the real thing. I am an auditory learner, so I like to attend lectures, and I don't think the Air & Space museum has many of those.