Chiming in here for the "yes, we like formal night" side and give Lynn some moral support. Alan and I like formal nights too. Please don't throw your stilletos or men's formal shoes at us :D .
Especially on longer cruises with lots of sea days, having a formal night breaks up the monotony for me. Plus it's fun to have special nights on cruises. However, I agree that 7-night, port intensive sailings should do away with formal nights and be all "elegant" casual.
