I am not the museum type but the Museum of Flight at Boeing Field is worth going to. If not to walk through the first presidential jet plane, (that would be Air Force One when the Presidents Eisenhower, Kennedy and Nixon flew on it), you can go inside a Concorde supersonic or see the tons of aircrafts inside the museum. It could get a pit pricey, but from 5:00 pm to 9:00 pm on the first Thursday of every month, admission is free and some exhibits are closed. Check their website.
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