I have finally achieved enough wins/losses in the casino that they said "where do you want to go?" and "the casino will cover it." So they comp'ed a Haven Courtyard Penthouse with large balcony. While I have been on many cruise lines and ships, I've never used a butler/concierge on a cruise before. What is the proper amount to tip for a butler on a 7 and 10 day cruise where the butler does not do anything unusual (no parties, events, etc.)?