I don't know, I guess my wife and I are semi-planners. We sail only small ships, so there is no need to study ship layout, but we do enjoy researching the ports we're visiting.
We'll pick out the things we want to see on each island, but after that its kind of all "seat of our pants". The night before a port we'll usually come up with a game plan for the next day, but that is always subject to change.
When we wake up in the morning, we'll talk to the various friends we've made on the cruise and if they're doing something that sounds like more fun than what we planned on, we'll do that instead.
We always make sure we see the things we want to see, we just may not do it in the way we planned. For us its much more fun and relaxing to make it up as we go along!