I am not a cruise holiday person, have never been on cruise before. I will be working on a couple of cruises next year, various cruise lines as an instructor/staff. I will be dining with the guests, making myself available to socialise, going with them on trips etc. I have plenty of smart/office style clothes and "ordinary" dresses, but absolutely no idea of what is expected on a formal night. Full on floor length dresses? Or trousers and a sequin/sparkly top?