Saw it last summer, wasn’t that impressed with it. The tour starts with a 10-minute movie in the visitor center, then everyone gets herded onto buses and driven a mile or so to the factory. Park outside, take stairs down into the basement, walk to center of factory, take elevator to observation deck, where the tour guide gives a brief narration of what happens in this part of the factory as you gaze out over a collection of partially-completed aircraft. Sorry, no photos allowed. Then you go back out to the bus, drive a couple hundred yards down the factory building, and repeat the ingress/observation/egress cycle. Repeat again, then head back to visitor center. I found that visitor center to be more interesting, since it had a number of airplane parts (engines, 747 vertical stabilizer, 787 fuselage section) on display.
If you’re in Seattle with limited time, much better to visit the Musem of Flight. It’s absolutely massive, and has some very cool planes on display:
-Air Force One, the one that carried Kennedy et al. (you can walk through it)
-Concorde (also walkable)
-“City of Everett,” the first 747 ever to fly
-space shuttle trainer
On the east coast, Baltimore has the B&O Railroad museum. Less about science and technology, but lots of history, and a large array of beautifully restored rolling stock.
Engineers visiting Washington DC must see the Smithsonian Air & Space Museum - the one on the mall, and also the Udvar-Hazy center.
Years ago my brother worked for General Dynamics in Forth Worth, and he gave me a tour of the mile-long F-16 assembly building there. I don’t know if similar access is given to the general public, but it’s worth looking into. It was like the Boeing factory tour, except I was close enough to touch aircraft parts.