I'm guessing you're asking about Magic Kingdom, but I'll give you some general eating advice and then suggestions for each of the 4 parks.
*Burgers aren't always a great bet. The buns are kinda weird.
*Coffee is bad just about everywhere.
*Pizza also gets mixed reviews. I'd choose other stuff.
*The hotels on the monorail have pretty good quick service restaurants, too.
*Sit down places almost all need reservations made well in advance, which you can make by calling 1-407-wdw-dine.
*Buffets are expensive, but if you've got a bunch of linebackers or bulimic sorority girls (oooh, the stereotypes, sorry. but ykwim.) they may be worth the money.
*All the parks have fresh fruit. Magic Kingdom even has baked potatoes. Cheap, filling, good.
*You can always ask for a glass of water at a counter service place.
*Check out menus and prices before you go at
www.wdwig.com under "Dining"
There are "reasonably" priced places in each park.
In Magic Kingdom, I'd recommend Cosmic Ray's. Good roast chicken and ribs platter.
In Epcot, I'd recommend Sunshine Seasons. Excellent salmon and veggies.
In Disney's Hollywood Studios, I'd recommend Backlot Express. Pretty good salad.
In Animal Kingdom, I'd recommend Flame Tree Barbecue. Super good ribs and pulled pork.
Have a great trip!