My parents have had alot of luck on the video poker machines. On our last cruise aboard the Dawn Princess, they hit for a $1,000 on the .25 machine a couple times each and, between the two of them, came home about $4,000 ahead overall. On the cruise before that aboard the Sapphire Princess, they had a couple $1,000 hits and many $200 hits and came home about $3,000 ahead. They usually limit their time in the casino to two hours a day or $50 each (whichever comes first), so they have had alot of luck with just a very limited amount of time spent gambling.
I play Blackjack and usually manage to come home $200 or $300 ahead for the cruise. Once I was very lucky and came home with $1,000.