At the risk of provoking the IRE of the forum, I would advise 24/7 supervision! The ladies are 17 and 21. You should consider spending a bit more and go to the west end. Somewhere like Rockhouse or Tensing Pen. I am sure the ladies are savvy and have good heads on their shoulders. I also do not want to perpetuate that they will be harmed by crazy locals. There will be aggressive male suitors, however. Somewhere like Rockhouse is a very good alternative. They shuttle to the beach / skylark and both locations are safe and worry free. You can have your cake and eat it too, but not at Fun Holiday or some of the other beach options. You will be just fine and enjoy your reach. The young ladies coming along would be a variable that would limit my choices of accommodations / environment.