If you dont care about the miles but want to check in quickly..use the Instant Travel Kiosks. They have them AT the ticket counter in Seattle, and just about everywhere else you turn in that airport. If you have bags, its best to use the ones at the counter. You go through the check in process on the machine, then an agent will come to tag your bags. The line is much much shorter, if there is even a line at all. You can also check in at the curbside Kiosk and leave your bags with the skycap.