All of the major mid-priced lines will have two formal nights on a 7-night cruise. On NCL, there are more alternatives for those who do not wish to dress up. I see a larger number of men wearing tuxedos on Princess than Carnival and NCL. Celebrity has two additional nights where men are encouraged to wear sport coats. It's a little more formal than Princess. I haven't been on a HAL cruise.
I wear a tuxedo on formal nights. If I were in a dark suit, I wouldn't feel out of place on Princess.