I always ask for the airline discount on food/drinks and then give a nice tip plus the discounted amount to the waitress/waiter. If they don't want to extend the discount, they are essentially letting the restaurant/bar keep their money. How clever you say. Van drivers $1 tip unless they are really great at which there is no limit. Gave a very nice driver in Denver who operates with his wife a $50 tip once to take his nice wife out for dinner after a long day. He literally cried over it but I just said "Hey, I'm a nice guy, what can I say" I am also of the belief that a tip is earned. For poor service in any venue I am not apt to leave anything. No tip says " Your service was lousy".