Carnival is not alone in offering this kind of two-tier dining. (Read my thoughts on this latest way for cruise lines to add to their income)
From my experience, Carnival's Supper Clubs' steaks rival those of the most famous upscale chain restaurants but you'll have to scramble to taste them or anything else on the menu.
These restaurants are extremely small compared to the total number of passengers, so make reservations as soon as you can, either online or as soon as you board.
Supper Clubs currently are available only on Carnival Legend, Carnival Miracle, Carnival Pride, Carnival Spirit, Carnival Conquest, Carnival Glory, Carnival Valor, Carnival Liberty, Carnival Freedom, Carnival Splendor and the Carnival Dream.
The following menus contain all your dinner choices:
Entrees (not a good place for a diet)