First, don't give up on USAirways just yet; I'd not be shocked if DOJ rejects the merger yet.
My experience w/ USAir is limited, but has been generally favorable, w/ a couple of caveats.
One experience (old, but it stands out) involved a trip IAH-Islip (sorry I don't know the code..), x PIT. Departure delayed because of gate-hold (ATC computers down, they were using broadband radar for flight separation, lucky controllers!). Finally allowed to take off, the pilots poured it on and made up a lot of the delay, but... Arrived PIT precisely at the time the flight to Long Island was scheduled to leave; FA's assisted us in getting off of the plane quickly, we RAN to the gate, and stumbled up panting, to a smiling gate agent, who said "You must be the Cutlers. We've been waiting for you." And they had.
We stepped onto the plane, the door closed, and we pushed back, slightly late (sorry to other pax), but very much impressed.
Oh, and (of course) the luggage did not make the change- so when it arrived on the next flight, US paid a cab driver to bring it out to us (in Southampton- a LONG WAY).
I'm not entirely sure you can beat that.
By the same token, on the trip back, we flew out of JFK, and the reservation agent did not tell us that the flight to PHL (connection) was on a commuter- a Shorts (as in, if you fly on one of these pieces of cr*p, you'll soil yours). Without a doubt, the most miserable excuse for an airline trip ever. But the PHL-IAH leg was fine.
So, my general impression is good.
But, last thought, I still marvel at the speed and efficiency with which US destroyed the value of what they had purchased after buying PSA. They (and AA, with its AirCal acquisition) paved the way for WN's California near-dominance.
For what all that's worth.
...three miles from BRONS, clear for the ILS one five approach...