Train
We take the light rail all the time from our home to the airport, easy way to travel to and from the city. (There is a station near-ish to the venue: SODO, it is a 1.3 mile walk from the station.... so probably best to not use this as your mode of arrival to the venue)
Flight
South of Seattle, large international airport.
Flight
North of Seattle, in Everett. Smaller airport.