Originally Posted by moondog
co/dl/nw -- i can only comment on nw because that's where i bank most of my skyteam flights. i like the lack of booking fees and the fact that you can make unlimited online changes for $25. this means i can fly from pdx to was and return from pretty much any airport in the eastern half of the us on a whim.
CO and NW require Sat night stays in order to qualify for 25k mile domestic awards.

Plus both offer below-average availability at that mileage cost, in my experience.