Excellent topic with thought provoking comments - I have been top tier at one time or another with NW,CO,US,and AA over the last 5-10 years and Mid-tier with DL, UA - I totally agree with the comments regarding DL - how can they fathom not letting PLAT's upgrade a companion ????? This one I don't get so DL don't get - I fly AA (Exec. Plat.) and am very content and you guessed it CO is also a favorite - I used to like UA but it seems that everyone is at least a PREMEX these days - seems like most flights actually have more 1k's than premiers !!!! my 2 cents - kazman