If you have young children and want to eat in a relaxed atmosphere there's plenty of choice in the U.S. Obviously a lot depends on where you are staying -- if you're in Orlando then you will have too much choice. On the beach in Ocean City you'll have to walk a few blocks. Fast food restaurants such as McDonalds and Burger King are ubiquitous.  Try to find a buffet style restaurant, like Golden Coral, as these are usually overrun with kids and for a fixed price you get an all-you-can eat meal. Pizza, pasta, cooked meat, rice, potatoes -- the list is too long to mention. And you get  ice cream and fruit. 

Kids are usually running around getting some exercise after that long drive, so if you want a peaceful meal in a child free zone, you've been warned. Shopping malls usually have a central Food Court surrounded by take-away food outlets - usually pizza, Chinese, subs (monster sandwiches big enough to feed the whole team) and loads of good value meals. (Restrooms in malls are always clean to a high standard - so don't worry about little ones getting ketchup everywhere -- washing facilities are excellent). If your kids are well behaved  then other outlets like Ponderosa (and loads more) provide a good meal off the menu and then you get to attack the buffet. Something for everyone. If you think your kids' behaviour is going to shame you, don't worry, kids are the same wherever you go. Just choose a restaurant that's full of other kids too.