I have flown from KSFO to KDFW to KJFK to London Heathrow, in a Concorde (Yeah, A really long flight) Without FG crashing, however on a different attempt from KLAX to KJFK in a 777-200ER, it crashed. One thing I can reccomend, is definately avoid Fly-By view, this drops the frames on my PC, sometimes causing it to quit. Another thing, is set lower visibility, giving you better Frames Per Seccond.
Another thing you can do is watch where you are above on the MP-Map, looking for whitch major citys you pass over, if your FG crashes, revert to one of those citys' airport's.
I would also suggest not to fly into KSFO, as I have done this before, and most the time it crashed on final due to the high levels of traffic, which is really anoying