I've been there a couple times, but not in the last two years (not since they added the 747 to the museum.) If you like space and aviation exhibits you should enjoy it.
They have a lot of nice exhibits that includes general aviation, commercial, military, and space. Everything from a Curtis "Jenny" to a V-2, an SR-71A, and a 747.
A non-aviation exhibit is their firearms collection.
You probably wont have enough time to really take it all in. Reminds me, I need to get back there again sometime this year.
EDIT: Here is their web site in case you don't already have it so you can try to plan a trip: http://www.evergreenmuseum.org/
