I don't think I've ever seen any cruise ship that has real hand-holding cards poker, -- except for some rumored games on Delta Queen, a boat that is not supposed to have gambling of any sort but was known for keeping the river boat tradition by holding some marathon poker games between passengers and sometimes even the crew.
For slots - I am pretty sure they have nickel machines, but why play 45 nickels, why not play 2 dollars instead?
I like to dally around casinos though I limit my losses. Unfortunately you aren't going to find casinos on ships that are comparable to Las Vegas in terms of odds on the slots (though are are pretty close to what you might find in Atlantic City). For example, video poker machines will pay "X" to 1 for
1 jacks or better
2 two pair
3 3 of a kind
6 full house
Where in Vegas you can find:
The live blackjack and craps tables are Vegas rules (probably your best bets). Video Blackjack you cannot double down or split.