This is one of those questions where it's: "Up to you."
I personally have never used a highlighter. Circling things on the program iwth a pen has always worked but a highlighter may be good for someone else.
I do carry a small travel size air freshner of Ozium air freshner. Just in case but have never had to use it except in the bath.
I don't use Post Its. I use a bit of ship's stationary for a note. If you do use a post it, please don't' stick it on the TV. More marks for the attendant to clean.
I do use a waterproof wallet for snorkeling. I find it invaluable instead of leaving valuables such as credit cards, and money on the beach.
Ziploc bags are nice for packing a sandwich or storage and take up little space.
Packing tips and lists are great but after awhile you have to figure out what works and makes sense for you. I often take a leatherman super tool and a telescope with me. I doubt that makes sense to many people.
Take care,
Mike