... how often do you let the restaurant know about it afterwards?
I ask because, it seems, people tend to complain more often about horrible service (or experiences) than they do about complimenting a restaurant for a great dining experience.
I think that it is important to let a restaurant know of both -- when it was bad, and what it was good.
People should be praised when they deserve it.
For example, the other night we went out to dinner and brought our own bottles of wine. Ponied up the restaurant's corkage and ordered. When the staff realized the wine we were drinking, the kitchen decided to throw in an extra appetizer to compliment our wines. They didn't have to do this and we didn't ask for it, but it worked out really great.
Later, we e-mailed the restaurant to note our sincere appreciation for the attention and service that they provided that night ... and they were very happy to hear from us and they even agreed to waive the corkage (should we BOYB again) on our next visit.