I have a friend who seems to have good manners except in a restaurant. She never says please and thank you to the waiter/staff. It bugs me!

That said, I often ask the waiter which of two meals they would order. I know they get feedback from other patrons and most places feed the waiters the same food you're having. I wouldn't know, of course, whether they're right about which is better, not having tried the other, but it works for me.