Hi Amy!
Unfortunately I can't answer your question, because I don't know how your family likes to dine, such as Quick Service or Table Service (full service), or what each member of your party would order off of a particular menu. However, I can provide you with some information.
You will receive your Disney gift card when you check-in. It can be used anywhere a Disney gift card can be used which is almost anywhere on property. However, some non-Disney owned restaurants and stores will not accept it.
With regards to the Dining Plan, some guests save a lot of money by being on it. Other guests don't save as much and some actually spend more by being on a Dining Plan. You can get more information on the various plans
here. I suggest looking at the menus for the various Quick Service and Table Service restaurants at the independent website AllEars.Net. They do a very good job of keeping their menus up to date. You can then compare the cost of being on the Dining Plan to not being on it and just using your gift card.
Whether or not you are on a Dining Plan, be sure to make an Advanced Dining Reservation (ADR) for any Table Service restaurants you are interested in.
Have a magical vacation!