I'd like to clarify the point earlier in this thread about preferring UA to AA/BA because AA/BA don't give miles on discounted economy.....
Actually, BA is the one that is tough with this, AA has always given miles on discounted economy, even on Web fares....
It is for this reason that I am AA PLT and not BA Silver/Gold....as I put my business on AA through Miami rather than the direct flight from Cayman to LGW (no way I am paying for a B/Y fare on my own or the firms money!)