Galley tours aren't as hard to get on as bridge tours are. I would ask the Loyalty Ambassador if it's possible. It isn't a perk for diamond members, but there are special groups that get tours. There is a limit to how many people can be on a tour. I've been able to take some of my friends on different tours, but I had to get permission to do that. When you become diamond plus, you get an invitation delivered to your cabin. I'm pretty sure there are no tours on 3 and 4 night cruises. I hope you get a chance to do a galley tour, you'll enjoy it.