As vouchers include tax and tip, you will always save at least a buck or two using them for character breakfasts - at the expensive meals you'll save more. Now whether the buck or two (or more) is worth the hassle of vouchers is another question.
Q&C vouchers, and to an even greater extent VKL vouchers (sit down lunch vouchers) MAY save you money depending on how you eat. For instance, a Q&C voucher will cost $11.50 (I think) through connections - a great deal if eating at Pepper Market and geting an $12.00 entree, a $2.00 pop and a $4.00 dessert. A bad deal if stopping at Pinocchio's and getting a $4.50 burger (skipping the fries) and drinking the water you toted into the park.