I will soon be moving out to PIT and I'm thinking this will be a good chance for me to reconsider my FF program memberships. I'm not really attached to any of my current programs as I have low balances (under 10K—AA and UA, 25K—DL, and 16K—CX which isn't very relevant).

My flying activity will be relatively light, with the most frequent travel being to my hometown of AUS. I also expect some shorter hops (less frequent) around the east coast, mainly to the NYC and DC areas. There might be occasional travel to SFO and abroad to Asia (both family), but those will be bigger trips that won't be regular by any means.

The main thing I have in mind is award availability—I'm hoping to use a smart program choice plus CCs to grant me some sort of mobility while being a student in the PIT area. I've heard that Southwest and US might be my best options, but I'd definitely like second opinions. Thanks!

US has the most flights at PIT. However, you should consider the possibility of a US/AA merger, presumably in oneworld, and the mess that the UA/CO merger seems to be. If you're moving to PIT for school (CMU?), does this location have a four year horizon for you?

Note that as a student, your CC opportunities are probably somewhat limited and in any event you should be careful here. In fact, during the academic year, your travel possibilities will be limited. Long weekends in DC and NYC might be incompatible with your studies.

Note that Southwest doesn't belong to any alliance and does not fly to China.

I checked on flights PIT-AUS for random dates next month. There are no non-stops, and the best fares for one-stop travel were on UA via Houston. USAir was notably higher in price.

US is the chief airline at PIT, but at least for now you can get credit on UA's Mileage Plus for US flights (as I do myself). My personal experience with award availability using UA miles has been quite good. In addition, UA's website is better than most in providing detailed information about award availability on its airline partners and in enabling booking award travel on those airlines without needing to phone.

If you have any kind of CC, you can pick up some miles on either UA or AA by registering the card with their dining programs (one program per card) and establishing a profile.

As far as travel to DC (where I live) is concerned, you may be better off driving or taking Amtrak. Flights won't save much time, especially if you need to go to BWI or Dulles to get a decent fare.

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.

If you're going for elite status, US Air. Otherwise, credit your US Air flights to United.

Would gaining status on US have any advantage over the same on UA?

It would if you fly USAir.