Few more:
1. Do codeshares count as BA flights (for purpose of the 2 for 1 certificate?)

2. I found BA flights from all these US cities to London: SFO, LAX, Las Vegas, San Diego, Phoenix, Denver, DFW, ORD, Houston, Atlanta, Miami, Orlando, Atlanta, Washington DC, NYC, Boston, Chicago, Seattle. But any suggestions on which to focus on to find open business class tickets? (Are some of these hub cities and others just have 1 or 2 flights?) So far I have found nothing from SFO but a lot from DFW. Any other tips along those lines?

Thanks!