thanks for the advice everybody.

i went ahead and booked BOS-LHR - seemed like all flights were more or less equal, except that BOS is shorter for me and there is one more plane making the trip an hour after mine. so in case of trouble with my flight, there is some hope at least.

booked outbound tues night (PHL-BOS-LHR) and return sunday night (CDG-ORD-PHL) of thanksgiving week for $250 each plus taxes for a total of $338 each. was also able to confirm VIPOW upgrades at time of booking, so i'm a happy camper!