Alaska weather can be very warm or quite chilly. Layers, with the bottom layer (on top
) ready to flaunt, works.
On other itineraries, be careful about the different cultures and know where their line is and respect it. I met a teenager and her parents on a cruise a couple of years ago. They were from am small town and the girl dressed gothic/rock/almost trashy. She was miserable one day when I ran into her out on deck because some locals in a port had try to buy her from her dad! I explained that at home, people knew her and knew her morals but what is normal in the US is considered blatant "advertising" in a lot of cultures. She felt a little better because she had not thought it out and took it very personally. I was just glad she was with her dad and not exploring off on her own.