Everyone in the dining room. With very little exception, kitchen staff (cooks, chefs, etc.) are not included in tips… even if the restaurant has a "chefs counter" or sushi bar where you are served directly by a chef. Unfortunately when the food is good, tipping higher never actually affects those doing the cooking. Occasionally when I was a cook someone would pay the bartender to give the kitchen staff a free round of beers after service… those were greatly appreciated.