Originally Posted by
TravelingZoomer
IIRC, Alaska does not do paid upgrades at check in
They do, they just aren't available very often. From as.com:
Can I pay for an upgrade?
If First Class seats are open within 24 hours of departure, passengers will be offered the opportunity to request a
paid upgrade at the time of check-in. This is available through web, kiosk, or counter check-in. For more information and pricing, please view our paid upgrade information.
Premium Class paid upgrades are available at any time from booking through online check-in, when you are selecting or changing seats. Subject to availability.