I just returned from Alaska. Took a Walmart nylon rain jacket, polartec jacket, one turtleneck, tee shirts, gloves, scarf and a warm hat. I used my sun hat, and the hood on my rain jacket. I did use my gloves and scarf when the ship went to hubbard glacier. I never used my rain pants or my pair of shorts. We mostly had partly sunny/cloudy days and temps in the 70's. It was cool in the evenings. In Ketchikan it was warm and sunny and went walking in my slacks and a Tee shirt.
Pack to use layers and you won't go wrong.