I am a frequent flyer with British Airways and it is always great transiting through London and stopping over. You get to work with three different time-zones (US, Europe and India) and I cherish this experience. I flew from San Francisco(SFO) transiting through Dallas(DFW) and London(LHR) to my end destination Chennai(MAA) on Thursday, January 23rd, 2014.
SFO to DFW:
My flight from San Francisco to Dallas was operated by American Airlines. As I need an Aisle seat to travel I always make it a point to do online check-in and pick a seat. On the British airways website, it re-directed me to the American Airlines site and was able to check in from SFO to Dallas and reserved an Aisle Seat for the 12:20 AM flight to Dallas.