You can certainly do both in a day as long as you start your day early in Vancouver. The drive is about 3 hours to Everett. If you get there in the morning, you could probably get on a 9,10, or 11am tour. Then you can have lunch and make it down to the Museum of Flight near downtown for the entire afternoon. The Museum of Flight is just a few miles south of downtown at BFI
. After you get your fix of aviation fun, I would recommend spending the night in nearby downtown, however it can be a little pricey. Staying up near Everett would be cheaper. Seattle is expensive, but is awesome for aviation.
Museum of flight and Boeing in Everett can definitely be done in a day, but make sure you can get tickets for the Boeing plant tour because they sell out early in the day. I would do Boeing first for this reason, though the Museum can get crowded, so I would recommend going on a weekday over a Saturday or Sunday afternoon. Also remember that the main border crossing at I-5 can get really nasty with lines (particularly entering the US) taking upwards of two hours. I recommend finding one of the less congested border crossings (there are a couple to the east of the main one 20+ miles) or getting there early in the morning.
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