A perk I would like to see for upper levels is priority disembarkation. NCL is probably at the bottom of the list for well organized disembarkation. A designated area, DR, theater, lounge is open to top tiers only with self assist luggage. Like embarkation, once the ship is cleared they call levels and escort you off the ship.
aside from a few employees, there is no cost to the ship. Zip, zero, nada. So nice on other lines to not have to stand in that extremely long self disembark line.