One of the best ideas I've tried, is figuring about $50/day for food, souveniers and mad-money per kid. This ensures that they each get to eat when/what they want, and no whining. Plus, I don't feel 'nickeled to death' by teenagers begging me to buy them a T-shirt, or trinket. If they have $300 in cold hard cash to spend during the stay, you would be amazed at how happy they are to eat a cheap hamburger, and how well they can save the money. Plus, I know up front how much money to budget for the vacation. My wife and I use our VISA, and because the kids have their money already, we haven't blown a budget yet. Works great for us; plus it teaches the kids to budget their own money. I'd rather have them learn now, and risk $300 on stupidity, than wait for them to hit college and get a credit card, and then be at risk for thousands. Teach'em young, and teach'em well.