One of my MBC instructors in Ohio has done a number of cruises and has done some training for the cruise line security staff. His standard carry is a good tactical flashlight and a stout pen or Cold Steel Sharkie marker. The tactics he trained are basically those taught in my DVD "Forever Armed," which focuses on improvised weapons selection and use.
Most cruise lines prohibit the carry of knives. Check the policy for your line to find out the rules.
If you want to "work around" the rules, you could look into non-ferrous knives, like titanium, G-10, or nylon. They're harder to detect on X-rays and magnetometers.
Crook-top canes are more convenient for some users because they can be hooked on your arm when not in use. For example, going down the buffet line. Hook it on your arm and "graze" with both hands. They also offer a few unique techniques that don't work with straight/knobbed sticks. My favorite is grabbing the shaft of the stick with both palms facing down. Raise the hook, nestle the tip just behind the bad guy's collarbone, then drop your weight and pull.
With all that said, I also prefer straight sticks...
Stay safe,
Mike