Here's the
web page that contains info on change fees with AS. In pertinent part (over and above F and Y tickets being exempt):
Alaska Airlines standard change fees are $100 (USD) per person fee if change made through an Alaska Airlines Reservations Call Center or $75 (USD) per person fee if change made at alaskaair.com. Change fee is waived when travel is wholly within the state of Alaska on flights operated by Alaska Airlines.
I was heretofore unaware of the intra-Alaska benefit.
Change fees are also waived for MVPG and MVPG75K elites.