I flew Delta BOI-SLC-PDX on Jan 1 as AS was booked solid following a bowl game in Boise; seat selection was out of the question as I had the last seat on both flights, but Delta waived bag fees and allowed me to board in Group 2 on both legs.
However, I will never again complain about the coach-class seat pitch on an Alaska flight. Delta's 737-800 had at least two more rows of seats compared to Alaska; I'm 5'8", and my knees practically touched the seat ahead of me.