Our guide was so wonderful that we wanted to tip her, and did so. Can't recall how much. Maybe $10 per person? No one else on our tour did. I doubt the guides get paid that well, and she was extremely appreciative. I would say it depends on the service you get. I've been on a few of these types of tours. Some guides are particularly friendly and solicitous, answering questions in detail, looking out to be sure everyone is involved and having fun, teasing the kids, etc. Others just go through the motions. See how you feel at the end of the tour.