Formal Night - It's your call what to do. There will be many people who take it to the hilt and many people who don't.
We've done both.
The only less than dressy clothing we're bringing with us are slacks and shoes for
The tails and tuxes have been fun sometimes and other times I have not been in the mood.
My advice is ... you spent the money on the cruise, it's your dime so do what makes you happy.
Dressing up can be a lot of fun and when we do dress up, we do it with a vengeance and take no prisoners, but personally, I see no reason when you're spending so much bloody money on a vacation that is intended for your enjoyment, to feel pressured into doing something you don't want to do.
For us, we have decided that this cruise is all about no schlepping, no dressing up and no costumes. The tuxes and other formal attire will be left at home. We will only pack dress pants, better shirts and shoes for our brunch, tea, dinner at Palo.
If you do for some reason feel that there's pressure to conform for dress up nights, Beach Blanket, Topsiders or whatever it's called is always an option.