A piece of advice....
Vouchers work well for a lot of things. Prepaying meals, giving one to a teen so they don't blow lunch money on video games and - MAYBE - saving money.
Look at the cost of the vouchers, where they can be used, and how your family will use them. For some eating patterns, they will save quite a bit. For others, a few dollars a meal - which may or may not be worth the bother - for still others people, the voucher will end up costing more than the meal would without the voucher - or to make the voucher worthwhile, they end up eating a dessert they wouldn't normally get (and perhaps don't want on their hips). It will take a little research and an understanding of how you will eat in the parks to answer these questions.
Just because someone thinks they are wonderful, or another family hated them does not mean they will or won't work for you.