I did a few cruise ship gigs many, many years ago at the time it paid $250 a week and included meals and lodge (which beat walking to shore every night).
I hated it at the time. The music was not enjoyable (can you say Tony Orlando & Dawn - or - The Carpenters).
The thing I really did not like - the cruise lines are very, very strict that you are the hired help and as such, you absolutely can not mingle with the guests (paying customers). We were very restricted in where we could go on the ship and when. We spent all our time playing - cause there was nothing else to do.
The good side was, I really got my brush playing (I played drums) together, cause everything had to be a very low volumn.
There were some really good players on the ships, but no one got to vamp much.
Oh yeah - make sure your reading cops are together.