First things first I would have hoped after a few visits that you would have assessed his character to not worry about him cancelling and keeping money. However at best he could likely get flight credit after paying a 200 dollar change fee. Some airlines like southwest dont have them.
If you are doing a full weekend or more than 24 hours try to have non sexual activities planned. Alot of clients too often see these affairs as sexual slavery with no plans for anything the guy may consider fun or entertaining. Good clients always buy gifts even if its simple things like apparel. They will remember you whenever they are in your sweater.
If you have must haves and dealbreakers state them but at the same time be able to go with the flow.