Do you need a locker?
We usually bring our own lunch, and keep it in a backpack on us. It lightens up after we eat, and we have room to throw the other various things we pick up throughout the day. Plus it is always good to hae a snacks and things on you.
I'll usually bring sandwiches or lunchables for the kiddos, and ready pak salads for myself. Just make sure you aren't bringing in anything glass into the parks, or any knife, even a plastic one. I had a giant sub sandwich onece, and the CMs at the security checkpoint reminded me to stop by one of the counter service places to grab a knife to cut it up!
My favorite place to eat is the lower level of the Hungry Bear resturaunt- it is a great shaded place to watch the boats and ducks go by.
Another good place is the carnation gradens, it is pretty out of the way.
In DCA my favorite place to eat is the Pizza Mow wow, but i think it might be blocked off right now with construction. The seating for the hot dog place by muppet vision 3-d is shaded and not to noisy to enjoy a meal also. The biggest table area is back by the sourdough bread/ chinese/ mexican resturants, but it is uncovered, and the noise coming from Screamin is a bit much for me.