ParisSantaFe

On the phone reserving LAX to LHR on AA136 with AA reservations when choosing a Main Cabin Extra seat, I was told by the agent that 17H, 18H and 19H all have an aisle on either side of them. On Seat Guru and on the AA site this is not apparent, however on Expert Flyer this aisle shows up. What's the story? And, would this seat be better? on a flight leaving in two weeks most of this cabin looks empty in the middle section. Would it be better to be in the H row, or in the D or E with no-one next, at this time... do these MCE seats fill up 24 hours prior? Would an aisle 17C or 17J with the middle empty and the window occupied be a better bet? and lastly, is this LAX to LHR on the 77W300 a better trip than the AA48 on a 767-300 in a middle section seat (rows 12 and 13CEG currently unoccupied).
Thanks for your help! Haven't yet flown on the 777-300