Hi.
I fly just about every week ... and use to primarily fly CO -- simply because I am EWR based ... and fares use to be competitive.
After 911, it has seemed like every other airlines fares have been much better than CO -- to the point where I can't justify paying the extra $300+ -- my company is flexible .. but will not allow me to take a CO flight when another is available for $300 less. I don't have any particular routings -- I am national -- but my experience for the last year has been --- I have flown every other airline more often than CO .... fortunately, I have 15K more on CO or NW to make 2003 plat (so sorry to see AmericaWest go - since I go west at least 1x per month)
Personally, I think CO fares in general, there are always some exceptions, are higher ... this will eventually hurt them ... as companies are tightening their wallets.