I have been on the Dawn twice and she is a wonderful ship. I have been on a 14 night in May 2003 and 11night Feb 2004, both very wonderful Cruises. Anyway, formal nights are planned around two picture taken sessions, the Captains Gale night, etc(so gather those bride maids gowns, and tux’s). Most restaurants are semi-formal, the good news is that you don't have to dress that way of you don't want to. I have done 5 cruises in the last year so, I am a bit jaded.
You will love it.