CLT,LAS,PHL,PHX are hubs for US Airways. PIT,BOS,DCA,LGA,FLL are focus cities. I guess LAX could be considered a focus city as well.
I thought they were considering LAS a focus city
Yes, LAS isn't nearly as big as people seem to think it is. And it's not just the West people--you'd expect them to assign an outsized level of importance to LAS--but the East people also seem to think LAS is larger than it is. PIT is similarly often thought of as still being bigger than it is nowadays. DCA, on the other hand, is much bigger than most people realize. Of course, I think Tempe bears a great deal of the responsability for how people perceive the sizes of PIT/LAS/DCA, since it has referred to PIT/LAS as "secondary hubs", but DCA as only a "focus city". Also, since there are clearly two very large hubs out East, I think many people want to assume that there are two very large hubs out West, creating a balance of sorts, when that's not in fact the case.
In terms of seats, from larger to smaller, it goes: CLT, PHL, PHX, DCA, LAS, LGA, PIT, BOS
In terms of departures, from larger to smaller, it goes: CLT, PHL, PHX, LGA, DCA, PIT, LAS, BOS