Welcome to FT!
Continental beats American (in FT speak: CO beats AA) hands down.

There are three major alliances:
Skyteam (ST), to which NW, DL and CO belong to.
OneWorld (OW), AA is there; CO is thinking of partnering with AA.
StarAlliance (*A) has US and UA.

Other airlines (like Southwest) do not belong to an alliance.

When you fly on an airline, find out which alliance they belong to and register a FF program (call it airline X). Each time you fly on an airline from that alliance, credit your miles to airline X's program, even if you're not flying on airline X.


This is what I would do: Since you don't like NW, look at other options. If you're flying a legacy carrier (CO, UA, DL...) find out how many flights to their hubs use mainline metal and not regional jets.

essxjay mentioned that if you fly on UA, you'll get E+ seats. That's true, however since you're flying into SFO, which is a UA hub, you're likely to have the same "hub" problem with E+ seating, etc.