One of our favorite places for lunch or a snack is White Water Snacks located right in Grand California. It's a nice break from the crowds you can run across at meal time in DCA or DL. Easy to access from DCA through the guest only entrance. (I've used this entrance many times and not had a problem. Kept receipt handy just in case.) You're staying at GCV so you can enter through that entrance anyway.
If you're lucky you may catch a glimpse of the calico cat that hangs out there.
Here's the hot dog, with chili on the side and fresh fruit (strawberries) instead of fries.
I've gotten the french dip, chili dog, and chicken nachos. I like to order some of my dishes with toppings on the side. (don't like my hot dog bun to get soggy, hate cheese sauce-only order shredded cheddar on nachos, etc.) Since it's like the hotel's food court they have a microwave right there you can use to heat up your food, if needed. I use it to melt my cheese

They also have a toaster.
The kid's meals are pretty good though my DD10 says the burger is too small now for her. She usually gets the chicken strips meal. A generous portion.
For sit down I like the Pizzetta Salad at Wine Country Trattoria in DCA. Most of the seating is outdoors so lunch is a perfect time to eat there. It's currently closed (for renovations?) so I don't know if it'll be open when you go.
My DM and I share this and it's plenty.
The only negative about WTC is there breadsticks are served cold, and I don't mean not hot, I mean cold.
Another one we like is the Jazz Express in DTD.
Fried shrimp and fries. Really good and a lot of shrimp!
Gumbo Yaya (good and a little spicy) and kid's chicken with regular fires (subbed for smiley face fries)
Another good CS with indoors and outdoors seating is Redd Rocket's Pizza Port. The Count Down Chicken Fusilli is excellent as is the Asian Chicken Salad.
The Plaza Inn is another good choice. Their fried chicken is excellent. 1/2 a chicken-totally shareable especially for lunch. You get mashed potatoes and a veggie. The green beans aren't very good so last time I got double potatoes. You also get a biscuit. Their pasta with Chicken Alfedo Sauce is good and similar to the sauce at Pizza Port-which makes my DD happy.
For a snack we like to get ice cream! We usually share a 2 scoop sundae and if I'm sharing with my DD10, I get the sauce on the side so I can remove her scoop of ice cream before I sauce mine.
And one last one, in Dec. we were there to see the fireworks and snow and since it was cold we went into Riverbelle Terrace for something sweet and warm. I go the chocolate mousse cake which was very good. Many of the desserts at DLR look good, but don't taste as good as they look. This one does. It's chocolate cake, fudgey brownie, filling, and fudgey icing. Good and sweet. We brought our own tea bags and made tea with the free hot water they'll give you.
Oh, and of course dole whips. Not the floats so much, but the whip.

HTH, enjoy!