We've always tried to walk a fine line between rewarding good behavior . . . and encouraging an attitude of entitlement. For example, when they were little, if both kids brought home good report cards, we'd go out to eat -- their choice, which was almost always Pizza Hut. When they earned a big award in Girl Scouts or did something big in church youth group, their daddy often brought them flowers from the grocery store. Small rewards, "right sized" rewards.
You can go too far in not acknowledging children's accomplishments -- yes, even things that are "expected" like passing your grade in school. Just as you can be overly generous in rewarding those accomplishments, which can definitely inhibit development of internal motivation.