Benjamin,
I was just at Walt Disney World with my teenage daughters who, like yours, don't have the largest of appetites. They regularly ordered kids menu selections. They were just a better match to both their food preferences and hunger levels.
As for larger portions of kids' menu selections, I don't think that Disney offers that kind of option. But I think you will find that there are plenty of counter service destinations that offer standard American fare in adult portion sizes. Here are a few recommendations, by park.
Magic KingdomCasey's Corner (hot dogs)
Cosmic Ray's Starlight Café (burgers, salads, and chicken)
EPCOTConnections Eatery (burgers)
Disney's Hollywood StudiosBacklot Express (burgers)
The stands along Sunset Boulevard (pizza, burgers, and hot dogs)
Disney's Animal Kingdom Theme ParkFlame Tree Barbecue (BBQ)
Restaurantosaurus (burgers)
BONUS TIPChicken Strips. Chicken Fingers. Chicken Tenders. Call them what you will, but you will find they are prevalent throughout Walt Disney World, offering a universal option for kids who are a bit pickier.
Please feel free to
write me back with more details of what they like, and don't like, and I can make some more recommendations.
Have a Magical Vacation!Doug