CiCi's is cheap. There are some Mexican places that have huge portions that could be split. Some of the local Steak n Shakes have free kids meals on the weekends. Beef o' Brady's kids eat free on Tuesday nights. There's an app out there of kids eat free places. You may also want to consider buying an Orlando Entertainment book, tons of Buy One Get One Frees, also has 4 $5 coupons for Winn-Dixie in there and lots of putt putt coupons.
Also the World's Largest Mc Donald's is close by, I think on Sandlake, near IDrive. My kids loved going there, they have the normal Mc. D's food as well as more "gourmet" items.
Giordano's Pizza is close to DTD and has huge yummy deep dish pizzas. Hubby and I get a small, I can only eat one slice, sometimes he can eat two. I imagine a large would feed a lot.