It matters what ship your going on to get aw with just a nice shirt.You could probably get away with wearing a nice pair of long shorts in the casual dinning rooms.But in te nicer ones you would need to wear your pants.
Lada Luck and Luv
Hey im a 15 year old guy and i just got off the Pride. I wore like kakie structure style pants with a nice collared shirt to informal dinner. On the formal nights i wore nice kakie pants with a jacket. As for AF tees to dinner, wear those during the day. I normally wore a AF tee with board shorts during the day. After dinner, i would wear shorts with a collared shirt, sometimes a AF tee. Hope i was help. have fun