I am thinking about visiting Seattle next year. I am trying to decide whether to fly or drive, because it would probably be as cheap to fly there as it would be to drive. (I live in Oklahoma)But that means either renting a car or public transportation.

Catch the Sounder, come out of the station (which is actually a funky "mall" of sorts in an old freighthouse), cross the street to the Link (free lightrail in Tacoma that only goes about 2 miles one way), it'll drop you off right at Union Station, and I believe there are signs to direct you across the pedestrian bridge to the museum in question. Be sure to check the Sounder schedule, though!