Welcome to FlyerTalk,
jomuggs!
I think the answer to your question would depend upon where you're going to be traveling.
But, saying that, I'd suggest looking at Alaska Airlines (that airline's HQ is in Seattle and SEA is their major hub) or one of the airlines that have partnerships with Alaska. You can fly on Alaska's flights and earn miles on your choice of several different carriers, and vice versa. You can find more details at
www.alaskaair.com and on the Alaska Airlines forum here on FlyerTalk.