I've been doing us-asia 3-4 times the last couple of years. I've found that on such a long trip, the higher cabin pressurization and humidity in the Dreamliner (787) really does make a difference; I don't get woken up mid-flight by a dry throat as much on a 787. I've also found that my jet lag is over in 2-3 days when flying the 787 vs 5-7 on a 777. Because of this, I would sacrifice the direct aisle access. If that is really important to you, try to get a D/E seat and you're good.

Not sure if the 77W is sCO, or sUA, but given that they are on the old 747 routes, I suspect is sUA. I've found that the sCO international flights more often than not have better service; the sCO crew tends to be a less "tenured" (read less jaded/entitled, more enthusiastic).