HI.... We generally figure about 100.00 per day. We tip on our own and go to the Purser's desk when we board and have them remove the tips from our account. We like tipping at the end of the cruise, that's just how we do it? I know we generally spend less then 100.00 per day but like the other poster said its better to estimate high. I like to play Caribbean Stud Poker, it's a slow way to lose some money and once in awhile you might come out ahead! We also bring our own wine onboard as well as a bottle of Rum in our check luggage so we can make a drink or two that way.
Hope this information helps, as well as what the others have suggested.
Enjoy your cruise;
Lee & Kelli