We just started saving up (and researching like crazy) for our family's first trip to WDW (squeeee!!!!). I have 2 containers sitting right in the middle of our dining room table for saving money for the trip. There is an empty oatmeal canister with a slot cut into the lid for the change and a large wine bottle for the paper money (both decorated in Mickey, of course!). Any spare cash we have gets rolled up and shoved into the wine bottle and because the neck is long, it's impossible to get the money out without breaking the bottle.....thus, no pilfering of the Disney savings. My kids have 'work for hire' jobs that they can do to earn money after they do their normal household responsibilities. We've negotiated pay rates for those things and every Saturday they get paid for what was done during the week. They've both decided their pay will go straight into the savings jars. Also, I put 50 cents per chapter book they read (they are 1st and 2nd grades, so books with chapters in them are a big deal) into the jar.
Also, we save a bunch of money on souvenirs anywhere we go by doing the same thing. I buy each of the kids 1 or 2 canisters of mini M&M's and let them have a treat. Then, I take the canisters and stack quarters and pennies in each of them like this: 2 quarters, 1 penny, 2 quarters, 1 penny, etc.). Wherever we go for vacation, my kids carry those canisters and look for the penny squisher machines (there's a penny finder app for smartphones...that app is GREAT!). So, for 51 cents, your kid has a little souvenir that they got to pick out and in some places, even squish. We have pennies from all over the place: Philadelphia, Pittsburgh (we live in PA), Cape May, Wildwood, OBX, Myrtle Beach, Alaska. They each have a book that they put the pennies in and its fun to look at the different designs.