First, I lock everything that is going on the ship. On my first cruise I was ignorant and did not lock my luggage. Guess what? When I disembarked I was missing jeans and various other items.
Second, you don't want to drag a large pieces of luggage on the ship. I always pull a pilots bag off the ship with me (my souvenirs are inside). I do take a change of clothes for dinner for each member of the family and carry it on the ship. Last cruise, my sons clothes and his fiance's clothes did not arrive at the cabin before dinner. They were embarrassed wearing jeans and t-shirts in the dining room.
Third, Porters always appreciate any tip. My dh tips $5.00 for 4 or 5 bags.