If you have any internal flights, they are quite strict on baggage allowance. One of the nice things about warmer weather cruises is that light tops and bottoms don’t take up too much room.
As to footwear, I can’t really walk in sandals - I have the feet of the princess and the pea. I also wear shoes with orthotics, so I went for the white New Balance walking shoes with mesh tops. If my feet were’t as sensitive, running shoes would have done. For indoor wear, my sandals (open back) serve to walk around the ship and as slippers. And, since our ship had a small pool, a pair of rubber thongs.