I typically set aside more than we need in savings just in case and then in the parks we use plastic exclusively. Heck in everyday life I use plastic exclusively. Just swipe and go. I don't necessarily keep track of every dollar, but I'm usually pretty good at estimating how much we need. We know what restaurants we have lined up so I know about how much I might spend on food. The only cash I keep is for tips and I have to have those in pre-made envelopes because usually I don't have cash. When we get home I pay off the plastic and start saving for next year. We aren't crazy spenders anyway, but when on vacation I don't want to worry about money. I spend however much I think I need to with full confidence that we have saved more than enough.