There are no non-stops to AUS on any airline from PIT. I've flown that route many times in the last year. From PIT, you can count on getting to hubs (PHL, CLT, PHX, DEN, ORD, ATL, DFW, LGA) and a few west coast/Florida cites, intermittently. And for some reason, Hartford.

Yes, there are others, but US continues to shrink, others come and go - you should make your decision based on connecting through a hub to get anywhere. I have lots of legacy US miles, but AA was as good a choice as the others, and I did a lot of DFW flying last year, so I'm with AA, hoping for a merger.

Unless you want to go with Southwest.