Been a Mileage member for about 7 years, before was mostly Southwest unless Continental/United for longer hauls.

Southwest gives me more flexibility flying out of San Jose, i.e. SNA and Vegas without having to lumber up to SFO.

However, the East Coast non-stops more than make up for it. If there is a non-stop option to fly Alaska over Southwest, wouldn't think twice nowadays even with a reasonable fare increase.