(Rearmost twin seats)
If you're travelling Y as a couple I think they're the best 747 seats as you're guaranteed no-one next to you.
There is also that club which can be joined.
However (as setaguru warns), the lavatories can be high-traffic areas even during darkness and the final aisle seat becomes a handrail for the urined-up, chatting backpackers awaiting their turn at the head.
BOFH