A west coast hub would be good and could be used to build up Asia more (or the could merge with UAL and get Asia that way).

SFO is very delay prone (fog). IIRC, LAX is supposed to get smaller not larger. I would think SJC could work if you can get in during a tech boom. They want to get an international destination other than Mexico again (not since AA canceled the SJC-NRT flight have they had this) and they are in the process of building a new terminal building (due to open sometime in 2010). So, the city leaders might give an airline incentive to fly out to some place in Asia or Europe. Problems with SJC are the ability to get the gates in a pattern that isn't a straight line (SJC is on a pretty tight property with very little room for expansion), a curfew (11:30 - 6:30 every night and you have rich people on both sides of the airport who won't budge on this), and running both runways could be tricky (though they are both 11,000'). It's difficult to picture a good west coast city.

Otherwise, I think DEN won't work for the reasons stated above (it's not that big of a city anyway).