dressing for dinner

We're going to the Allegro Bavaro and are taking our teenagers with us. For dinner I know that men need to wear long pants, but what about a 19 year old? My daughters are 17 and 14. What should they wear to dinner? Help!!

My friend and I are 17 and 16, we went to a different resort but I imagine it's much the same. For dinner we dressed up on one of the nights when we went to the restaurants, when we went to the buffet we just wore shorts and tank tops or short-sleeve shirts. At the restuarants casual dress was fine too.

For females you can wear pretty much whatever you want. It's the men they would like to NOT see shorts at dinner time. Thanks.