Sorry, don't have a current menu but I would not say that there are any "not to be missed" treatments to be honest. You will pay 2 - 4x what you would pay at a spa on land, plus a mandatory gratuity. You will most likely get a hard sell on the products that are used in your service (which offer a large commission to whomever is selling them.) In my opinion you are better off getting that mani/pedi before you board.
As far as facilities, the spa sauna/whirlpool/etc are just lovely. Not sure if you are YC or Aurea, otherwise you can buy a day pass. That's a nice way to spend an afternoon.