Island Princess-Alaska in June

Hello all...going on an Alaskan cruise in June on Princess line. I am wondering what to pack for dinner apparel. I have read suggestions all over the map. Can my husband wear khaki's and a button down shirt? Can I get away with black slacks and a nice top? (we don't want to stick out like "sore thumbs").

TIA :-)

What you mention works fine for all the smart casual nights. And these days, it probably works for formal night as well. Some people still do the full-on formal thing these days, but I've seen a lot of people who don't.