Shoes - If you want your shoes to last, you need shoe trees. Ones made from cedar. They'll preserve the shape of your shoes, prevent them from developing deep creases, absorb moisture, and even make them smell better. They're a no-brainer.
Best cruise idea - take a hanging shoe tree, fill it with your toiletries, jewelry, over the counter medications, etc. Pack it full in your luggage, when you get to your cabin, just hang on the bathroom door. Keeps your counter free of clutter, and I have to believe the room attendant loves not having all that stuff on the counter too!