The EK 340-500 has a crew rest area in the aft lower bulk cargo compartment. Access is from the aft galley. It is down the stairs with seperate area for flight deck and cabin crew. It has an electric heat system that is turned on in preflight by the flight crew. If they forget and the compartment gets cold soaked you can forget it. It is like sleeping in a ice box.
I have not flown the 340 as yet, but friends have told me it is very easy to get good rest.
As to the 380, initial data from Airbus is that the flight crew rest area will be accessed directly from the cockpit with stairs down to the rest area from behind the captains seat.