And here I thought you wanted advice on ANC, my hometown, which unfortunately I haven't visited since 1989.
AS is a fine airline. Sit on the left side of the plane ANC-SEA for a great view of the coast, if you're flying during the day.
Look on AS' website for seat maps, some seats have better pitch than others.
Don't worry, it'll be fine. AS is one of the better domestic airlines. Be aware you can credit your miles to AS, NW, CO, AA, LA, KL, BA, or CX, if memory serves.