We have just done LA and back on a BA380 - both ways on the upper deck, and in 53J and 53K. Coming back overnight we were not overly disturbed by the crew in the galley - although we have had that problem on other flights. There were certainly upper deck jetties at Heathrow.
The front of the upper deck would be my preference as the only through traffic is to the forward bathrooms as they rope off the forward stairs. As said, the bathrooms are huge.
The back row does have unencumbered access to the aisle, but the aisle seat will still have the person from the window seat in the row in front climbing over you to get out. This was more disturbing on our return than any galley noise - mostly because of the biff in the row in front.
The upper deck window seats also have useful storage bins outboard of the seats, as a result of the curvature of the fuselage and there only being 7 seats across vs 8 on the lower deck. The downside of the sloping window is that the view is slightly less good from the upper deck.