My wife and I just spent a week there. The first few mornings the credit was $15/person and at some point it switched to $18 a person. As others have said, this mostly covers the cost of the breakfast, which we thought was very tasty.

Note that they do add the tip directly onto the bill at breakfast. It's labeled as a 'Service Charge' or something like that, and we asked to confirm that this does go to the server. We ate at the bar a few times and they don't do this there, only at breakfast.

AGS