Just read this "horror" cruise story. The wife's checked bag went to wrong ship. They checked everything and went on ship with just the clothes they had on. The couple made at least one big mistake. Always carry on a bag with "just in case" items. Another thing they did that I wouldn't do is trust the parking lot company to transfer the luggage. Yes the company taking the bags is ultimately responsible but there are things we can do to reduce the impact of goof ups with luggage.
http://www.nottinghampost.com/couple-s-nightmare-cruise-after-their-suitcase-is-placed-on-the-wrong-ship/story-30297634-detail/story.html