From Todd at my inquires about the advantages of various Frequent Flyer programs. -- AdamShand
> i was curious who you thought the best airline to get a frequent flyer account > with was. alaska isn't nearly as useful as they used to be :)
Well, that's a hard question to answer. Have you gotten a job where you're going to be doing a lot of travelling?
Portland isn't really a major hub for anyone. Delta has made noises about making it a hub, tu it hasn't really happened. With your Alaska account you can accrue miles on a lot of domestic US airlines (NW, KL, CO, AA) as well as the couple of int'l airlines that you're probably interested in (BA, QF).
American is a pretty kickass airline, but for domestic accrual, you basically have to fly them or TWA (which will soon be folded into them, as they just bought TWA.) The major alliance they are a part of is called OneWorld. Check it out at http://www.oneworld.com/ They also have the added benefit of their more room throughout coach thing which is NICE.
I don't like United at all as an airline because I have no status with them. Basically they suck as a one off, but if you are going to be flying them a lot it would be worth it to go for Premier Exec. They are a part of the Star Alliance. For domestic accrual you fly them or DL.
With Northwest you accrue miles on CO as well. Int'l partner is primarily KL, but it gets interesting because basically NW and KL have a joint operating agreement so you get a chance with a bunch of smaller European airlines. Your AS miles would also accrue here. 
Don't know much about Continental, but they consistently win Freddies. (The award for FF mile programs). Check them out at http://www.onepass.com/
Also, check out http://www.flyertalk.com for more than you ever wanted to know about FF programs.
So, I'm not sure if I helped or not. Basically take a look at where you like to go and find an airline that does it and then fly them consistently.
Good luck, Todd
AA = American Airlines AS = Alaska Airlines BA = British Airways CO = Continental Airlines DL = Delta Airlines KL = KLM Royal Dutch Airlines NW = Northwest Airlines QF = Quantas Airways