We just used the Quick & casual vouchers. They worked great. It was so much fun to walk into a restaurant and try to spend the most possible. It wasn't that hard to spend $20 for a single voucher.
However, if you ordered all the cheapest stuff on the menu, then the value of your meal could be less than what you paid for the voucher.
The Q&C are good at most of the counter service restaurants in the parks and at the resorts. The voucher is for entree, side, dessert, drink.
I ordered mine from hotwire savings club They were about $12 each.
I hope this helps.
Chris