We try to break down the cost savings into things they want at Disney. If they want to go to the movies, we tell them that we can rent a movie from Redbox and save the $$ we would have spent on the movie and the savings would buy 6 Dole Whip Floats at MK. That usually does the trick.
Two of our girls are very thrifty, but one of ours has such a hard time keeping any $ in her wallet. We're not sure about the baby yet, because he's still too young to have a savings style.
We also have a set amount for entertainment each month and out of that comes going out to eat, going to the movies, renting videos, etc. Once it's gone it's gone. We let each of our three daughters decide what to do with the monthly entertainment budget twice a year, so they feel they have a say in what we do. The first month my oldest was in charge (when she was 7), she spent almost all of it on one venture out, so we had to remind her for the rest of the month that she'd already spent it when we went to the movies and for pizza and ice cream. The next time she was in charge, she stretched it out over 3 weekends. We think it taught her a valuable lesson.
Our middle daughter spent the entire montly budget in one outing with no regrets. She planned what we would do, we had a great time, and she had to be reminded a few times afterward that we'd spent the entire amount, but she was happy. She has continued to spend this way. It used to bother me, but she has a different spending style than I do, so I have to get used to it. I do constantly try to point out spending/saving/budgeting opportunities and hope she's at least taking note of them.
Our youngest daughter is very thrifty. We went to the mall because the girls had some Christmas $$ to spend and she gave herself a budget of $5 (out of $105) and she came back with $5 in her pocket because she didn't finad anything that she thought was worth parting with her $5.