Big Daddy's uses a service line (cafeteria-style). You can order a 2-meat or 3-meat dinner, and tell them whether you want spicy sausage, regular sausage, sliced brisket, or ribs. Everyone knows the key to BBQ is the sauce, and theirs is good...not too spicy, too sweet or too anything. They also have good sides (macaroni and cheese, potato salad, etc.)
The ambiance is the friendly workers, the television, National Inquirers, and some movie memorabilia on the walls. I felt comfortable and relaxed, although they would not win any decorating awards. They don't need it though...it's just good BBQ.