I love Five Guys, it's at the top of the heap in terms of chain fast food restaurants. There's not much on the menu, just burgers and hot dogs, with your choice of (free) toppings. The burgers are griddle-smashed and delicious. My one quibble is I wish the cheese was melted more. The fries are good too, and you get a huge pile when you order a large, enough for a whole family.
The room is great for kids, and you get free peanuts in the shell while you're waiting for your food. A great place to go for a relaxing dinner out with kids.