Kids Spending Money Tip

As we near vacation season, I've had a couple people ask me again how we teach our kids about money on vacation...so here it goes.
When we go on vacation our children are each given $20. This is their vacation money to purchase t-shirts, drinks on the go, trinkets etc. They get to choose, but when its gone, its gone, and "bank mom & dad"doesn't don't do vacation loans. This makes them think before they buy, and avoids the "I wan't" syndrome. They are not forced to spend it, they can easily save it and combine it with other money earned for a larger item. Of course we are paying for their lodging, meals, and entertainment (we are on a budget for this too), making this money more about souvenirs etc. that kids typically want or beg for.
Our kids do not get weekly allowances, we've tried it and it just doesn't work for us. Instead they have opportunities to earn money for stuff year long, but the bulk of their earnings comes from how they perform at school, and we pay that portion out at the end of the school year (just in time for vacation season). Our school system uses planners to communicate between the parents and the teachers, as well as inputting assignments. If homework is not done or behavior during school is lacking...that is where its logged. This can even be something as simple as talking too much in class, or not following rules. We can monitor how the day went by looking at the color of "face" they have each day, "smiley faces" being the best. Each week our children can earn $1 for simply having all smiley faces and homework done on time. If they have a lesser face, or homework not done, they forfeit that weeks money. Because we do not our children to think that is "okay" to misbehave if they've lost that weeks dollar, we start subtracting $1 from the pot for each additional non-smile face they have that week, with a potential  $4 loss. This math of course is a bit confusing to our Kindergartner, but for her, she understands the basic concept, and simply had to physically put the money in or out of a jar as we went along....her knowing that at the end what was in there was hers.
Why do we pay the school money out at the end of the year? Because this teaches them that not all gratification is instant, as well as the timing being good because summer is when we go on vacation, and this gives our children the opportunity to have extra spending money for this fun time. Of course its their money and we allow them to decide what they want to do with it, and sometimes they opt for one "cool" toy or to put extra into savings instead....but THEY choose. This has work tremendously well for us!