I organize trips among our friends. We had 10 for Palau, and 12 for Cozumel last August. We had 23 for Bonaire a year ago March. I am often asked for tip guidance as the organizer of the trip. I usually say "use your heart." But when pressed, I suggest 15%-20% of the dive operation, and suggest the same for restaurant staff and housekeeping. We usually have the same crew and DM's for our stay at SCC, and we don't tip the crew as a whole, but tip individuals.