There will be 3 formal nights the remainder informal or casual. Many men now wear a suit on the formal nights, but quite a few willl have their DJ with them it can vary but the kids just look smart or dress up if they wish. On the less formal nights ladies wear skirts or trousers complemented by a sweater or blouse. Gentlemen should wear trousers with a collared sports shirt or sweater. The formal nights are normal the 2nd day and the 2nd last day never normally the last as you have to be packed up ready for home with the other night somewhere in between depands on the ships itenary. These details you will get on your programme when you board, mainly as many ladies like to book their hair appointments on the day of the formal. The last formal is usually different when it come to the sweet course but you will find this out in time. Hope this helps others may add further information.
I bought my 2 sons aged 9 and 12 at the time a suit and tie each from Marks and Spencer for about £36 each I think it was. They both looked very cool and my youngest especially enjoyed dressing up like his dad. If this is too formal, then a v-neck tank top or light sweater would look equally as dashing.
My son wore long black trousers, l/s white shirt, a tie and his school black shoes for formal nights until he was 14 and then he added a blazer. At 18 he had his own dinner suit for university so that was OK. If they have no need of a suit in everyday life then don't buy on for the cruise. My husband always wears jacket and tie on less formal nights and jacket and open neck shirt, a relaxed look that still looks smart for casual nights. I always try and maintain a smart look and take dressy trousers and a long blkack skirt and mix and match the silk camisoles and floaty overshirts for formal evenings dressed up with jewelleryand silk skirts that co ordinate with the tops and shirts. I call them it my cruise wardrobe. Silk packs beautifully and takes up little room. Don't forget it can get cold in the aircon over dinner.
There is no real need for the children to have formal clothes, suppose it depends on their age. We took a large family on both RC and Princess cruises over the past couple of years.
My daughter (3 - 4) loves pretty clothes but really whatever suited - dresses and the like. The older boys, 12-18 wore either a smart shirt and trousers, or maybe shirt with a jacket. None of the boys wore a tie, exept for on one of the cruises we had a wedding.