They have not changed the formal nights - I love formal nights. I would say by far the majority of people dress up on those nights. I think it's kind of sad to see those who insist on wearing jeans to formal night - but it doesn't affect my cruise.
Celebrity Constellation - March 17 followed by Celebrity Reflection - March 22
44 cruises - too many to list however cruiselines are in no particular order:
and some unknown tub
formal nights ,most people that go to the main dinning room will be dressed for the occasion. smart casual is not really done anymore, but I personally dress in nice pants and collared shirt every other night. I am with felix, no jeans or ball caps any night.
Other than your 2 "formal" evenings, you can pretty much follow the dress code for casual nights. I wouldn't bother packing a sports jacket, just takes up too much room and you hardly see the guys wearing them, just a nice polo type shirt and docker type pants will do nicely. I understand they are allowing jeans, way to go!