USAIRWAYS.COM shows seats open because Ma&Pa Kettle don't want to buy Choice Seats or forgot to take seat assignments because they think they will get free "upgrades" or just Plain Jane forgot to take seat assignments...
TheHub is 100% Accurate except when Revenue/Yield Management is playing around with the Loads, as the Hub reflects ACTUAL booking levels (passengers booked on the flight including both "passengers with seats or no seats regardless".
I would go with theHub no matter what.
Sometimes flights will show no seats available because all seats that are left are also either under Airport Control especially the Boeing 757s (Bulkhead rows & Emergency Exits) or just the "Choice" seats.
