Sorry to be another voice for no go. The "Seattle" airport is quite
a way from Seattle and from Tacoma for that matter. Ground
transportation via Metro transit would take quite some time to get to
Dash Point ( in Federal way near Tacoma) or to one of the many West
Seattle boxes.

If it were San Diego, where you can get to Balboa Park in no time via
taxi, You could do it. But Seattle Tacoma traffic is notorious and
in September, likely you will have rain anyway ;-)

So enjoy your layover. Sorry to bring bad news.

I agree the notion of the havoc that a box IN the airport could
cause.... But it WOULD be fun. Would require a bartender or other
vendor inside the loop.

perhaps a code name drink at a certain bar would yield a box.

Hummmmmmm ????

Imagine a whole string of "airport boxes"