We just returned from a cruise on the Carnival Legend. We only attended one of the two formal dinners. My BF had on dark gray dockers, lighter gray shirt and tie. He fit in perfect, not to dressed up and not dressed down. You can stay dressed up for the rest of the evening if you are comfortable doing so. We had a formal photo taken, then went back to the cabin and changed back into our comfy clothes. Some people stayed dressed up, some didn't. You will find Carnival is much more relaxed than some of the other ships. That is why I like Carnival. Don't stress over it. Go and have fun. Also, shorts and t's during the day are just fine. Have fun.