DeltaFlyerToo, very good comments. It's true that US Air could have become a niche airline, catering to business travellers and therefore maximized revenue, had it not had the idea to acquire PSA and Piedmont, which ironically, were both well managed operations with similar philosophies. However, it is what US Air Group Inc. did with those assets that are one major source of the carrier's inability to turn around. PSA offered US Air the chance to grab a sizeable piece of the intra-California/West Coast market long before Southwest got there and United Shuttle was created. The Piedmont acquisition gave US Air a common fleet (737-400's, a few 767-200's, and those pesky Fokkers) but it also gave them CLT, which was and still is a robust hub but it never has been marketed as a cheaper, more stress-free transit point compared with ATL and never had, and never will, have the multiple connections that ATL can offer.
US Air wrecked itself through lost opportunities, poor management, lack of focus, high operating costs, and a poor use of good assets. Yet, it has a powerful presence in a number of key airports (LGA, BOS, DCA, PHL, and even PIT) but I think those assets will be better used by someone else.