Do any experienced cruisers have an idea about what the range of clothing suitable for Alaska, (June 30-July 7) might be? I don't want to lug along a winter coat if it won't be used, but I also don't want to freeze.
The key to cruising in Alaska is layering your clothes, so bring a sweat shirt or 2 and a few t-shirts and you can peel the clothes off as needed. We went late August and I packed like that, no winter coat and was fine. If you take any excursions into the Glaciers, thats pretty cold, so also pack gloves/mittens and a hat. I also threw in a pair of shorts and did wear them, we had unusually warm weather for the time we went. Also, expect to see some rain, you are in a rain forest, so be prepared for that, we only had one afternoon of rain in Juneau...
I would definitely layer! We were there in early July, and found it to be mostly temperate (long pants and a long sleeve cotton shirt was fine, but the one day we were close to Sawyer Glacier, we were freezing. We couldn't wait to get off the ship and buy some fleece. Take a fleece, maybe some gloves and a scarf and you should be fine.
When we were in Juneau we had beautiful weather and everyone took advantage by sunbathing for the time we were there. We had rain in Ketchikan, but they said it rains almost every day in Ketchikan.
Enjoy yourself, and take lots of film or extra memory for the digital. You simply cannot get enough pictures.