Well - I just came to Amsterdam from Johannesburg on KLM 747. The flight up is about 11.00 hours, overnight.
Had aisle seat in emergency exit at the rear - row 51(?) on starboard side.
Masses of legroom and a pretty good sleep - half civil to all the family on arrival and for that day.
Paid €50 extra for the seat and would do it again every time for a long haul night flight. Not for a day flight though.
Also - in this case, seat is right opposite KLM cabin crew bunk entrance door. In sleepy moments of being awake at night, allowed one to dimly view blue clad pretty girls climbing ladder - very restful and better than sheep!