Flint,
I don’t believe there’s a guideline for tour tipping. However, I’ve seen many people give a Courtesan $20 minimum for a tour. If more than one customer is part of the same tour, they usually all tip separately. If more than one man wishes a tour as part of a group, then they are usually accompanied by an equal number of Courtesans. A tour is a good way to become acquainted with a Courtesan so it’s wise for a client to select a tour guide with whom they are interested in partying.