I have sailed on 20 + Princess cruises. When we first started, we would dress up (no tux). He wore a suit and tie on formal nights and I wore sparkly pants and fancy blouse. Now it's unlikely to see a whole lot of people wearing tuxes and fancy dresses. It sure makes packing a whole lot easier. Now, on formal nights my husband wears nice pants with a collared shirt and tie. I wear black dress pants and a nice blouse. If you want to dress fancy you will not be alone. I would say probably less than 15% go fancy. I have seen a few times where people wearing shorts have been turned away from main dining room. I was on Enchanted the entire month of February this year and people generally wear nice casual.
Now, I'll be getting a lot of hate messages. Please be nice.