I got hooked on US almost by accident...
Last Feb., I was looking for the cheapest student fare to Germany from SFO, and since I had few miles in any program it came down to price. US beat out CO by about $10.
By the time I flew on the ticket two months later, I was just in time for the double Q-miles promotion. The return plus a one-way outbound (also student fare) made me elite.
I do need go out of my way to fly them (SFO instead of SJC, often lousy connecting times between west coast and Europe flights), but the benefits (especially SWU's and 50% mileage bonus) are hard to beat, and I enjoy stopping for a day on the East Coast to visit friends near BWI.
Yonatan
P.S. since discounted transatlantic fares to/from the West Coast are often only $100 more than from the East Coast, from a mileage-run perspective it's like adding a transcon for only $100!