Best way to west side of Mt. Adams, WA from I5 southbound

Thank-you for all your help. We were supposed to leave last Sunday but our Ranch Hand front replacement bumper just arrived today. That way we would have been out in the Nevada/Great Basin somewhere far from the madness of I5. We will probably go around via I5 then head east on 12. Or, use 20 eastbound then hit Mt. Adams on our return. I like where I live (and was born) but hate the drive through Seattle. Just plY it by the weather, I guess.