To get more out of the experience, I suggest (shamelessly) reading the following before you go: Dining in the Wake of History
I seem to recall that in the early days of the restaurants, each would feature menu items specific to the liner that inspired it. In other words, Long Island Duckling for Two was available only in the SS United States Restaurant. Now, it appears that they all have the same menu.
If you do go, I highly suggest the foie gras appetizer. JMHO.