One of my friends swears by USAir. I just switched.. I don't fly nearly as much as you do.. but I can attain silver status if I fly 25,000 miles per year on any type of ticket.. it doesn't matter if it is full fare coach, discount coach, or even a ticket off of priceline..

For me, this is the first chance I'll ever be able to attain elite status..

And since I am moving to London, that means I can basically do it in three round trips.
--Alex