Silicon Engineer: Your PSA miles were absorbed by USAir when the latter ate up our favorite airline, took all the planes back east, and practically abandoned the west. This process took about 3 years.
Almost instantly, the great 15,000 mi trips to Cabo disappeared as an award; the write-your-own-ticket ticket stock was invalidated, making us return once again to the travel agent, rather than tear off a ticket and fly (receiving a bill later), and the innovative frequent flyer program which allowed you to have your favorite seats in the profile, and really worked to sit you there, disappeared.
I was at BUR airport twice in the week USAir took over. Changed signage, but long LONG lines, late flights, and nobody really knew what the new procedures were. A few months later, we were all flying on triple miles bonuses, racking up huge amounts----- but then the disengagement from California began. No more service to Concord, Long Beach, or PSP. Then no more SJC. Then, the west coast north-south routes started to disappear; finally, in came Southwest, and you were left (here in SFO) with BWI, CLT, PHL and PIT. And the PA routes were scheduled either bone-chillingly early or late.
Finally, by about 1995, it seemed USAir had managed to take the best and largest airline in the nation's most populous state, and reduced it to a 8-flights-a-day, 2 gate carrier at LAX and SFO. Hope they got taken care of back East, cause we shed a few tears out here, which we've never quite gotten over.......... WN and UA Sh!ttle just can never replicate those days....