ha-ha you likely will not need a new wardrobe unless you are from Florida.
I lived in Anchorage for a year and their 70 degrees is like Oregons 90 degrees.
So act like you are going to Vancouver BC. Weather in AK should be great in the mid summer as will be scenic views. Alaska is a beautiful place to see. You can take long silk underware if you think you want an extra layer or some Cuddle Duds underware to extra warmth. You will want more than a wind break just pack in layers, sweat or polar fleece under the jacket and a hat and gloves just incase. Go prepared for anything or just buy what you find out you need along the way.
Smaller ships do the Alaska journey and seem to me to be less fancy.