Thank you all so far!

I will be working/living downtown with no car, so DCA will be a airport of choice. I saw that Amtrak's biz class fares from downtown to BWI are pretty good. The + to BWI is lower fares (even after the train) and more upgrades than DCA.

I will most likely be splitting between DCA and BWI. Cost is not that big of an issue, but I don't want to throw money away. When I'm arrving late leaving early I go with DCA, for mid day flights BWI, throw in a few IAD's and so on.

I'm leaning towards NW, AA (where I'm already PLT) or UA. With the new info, what would you guys say out of these three?