2Ruse, I'm looking at all of this, too and evaluating the options from the West Coast.
By the way, using MileMarker I came up with SEA-JFK-LHR as 5850 miles one way. I assume that's how Qantas and BA would count it as that's the actual route you would be flying rather than SEA-LHR. Probably a moot point anyway since the info is that Oneworld Awards can't be used on Concorde according to what has been posted on this thread.
If you come up with another way of doing this, please let me know. I'll gladly share any ideas/info I come up with, also.