I often fly into LAX to fly SQ or SEA to fly BA when travelling first class or biz primarily because of the grave discrepancies in ticket pricing. Pitiful really, but if i can help it and am paying out my pocket I will save the 2000-3000$ and fly to the closes major US airport. Mind you LAX is the official mascot for the worst airport in the world haha and SEA is far better. bottom line, I almost always fly into the US for most long haul routes.
cheers