Both UA and AA fly direct from Seattle to Tokyo so that is nice. BA has a direct Seattle to London but I can't get AA credit for it since they also fly trans-Atlantic. Neither carrier has a direct Seattle to London so I have to connect on the way through Chicago or SFO/LAX.

The thing that seems nice about AA is that you get to count the 25% mileage uplift for flying business class toward elite status, which UA doesn't give.

-Allen