Personally, we are not into dressing up on our vacation because vacation(for us) is time for relaxation - bar none.
I will lounge around the ship in my jeans because that is what I wear. However, if there are specific dress codes in the main evening dining aka sans jeans, then I will abide by that and wear casual pants and a proper shirt.
Understand there are three formal nights on our 16 day caper. I have no intention of dressing in a tux( never did, not now and never will), however I will pack my navy blue blazer, dress shirt and tie for formal night, that is if we decide to partake. We will probably take in one but that will be enough for us.
Just my view point.