This link appears to go to some kind of consultant advising Gray Line on how to extract more money from its customers. And how guides can increase their tip potential. Doesn't appear that evaluating tour quality, value, historical accuracy, etc was much of a priority. In short, these guys are "Them" --as in other side of table from "Us." It's actually an interesting peek behind the curtain. I'm surprised these consultants/analysts left the report publicly available to all and sundry.