Ah - but there is a trick to getting a seat on a sold out flight - it is called www.usairways.com.
On more than one occasion I have been told by the ticket counter that a flight is overbooked, and they refused to put me on a flight. However, I simply booted up my computer, went to usairways.com, and the web site sold me ticket on the flight, and gave me a seat assignment.
Then, I simply went to the kiosk and checked in. Guess some other passenger with a lower fare than me got bumped if everyone showed up.
Since I am travelling on business, the money wasn't really an issue, BUT - being told a flight was sold out and then being able to buy a ticket on it certainly did piss me off!
So the moral of the story is - I would say that the price paid for a ticket has alot to do with getting on a flight since the ticket I purchased was a last minute full fare.