I was on the mid-August Alaska cruise this summer. As far as waterproof stuff, we were
extremely glad we had ours. I watched the forecast pretty obsessively a couple weeks before we left, and when the extended forecast for the Ports showed rainy and mid 50s, I decided to invest in waterproof rain pants from REI to go along with our lightweight waterproof jackets. We used them in both Juneau and Ketchikan--could have used them in Skagway but it was less rainy that day. I was lucky--we have an REI store in our town, and they had rain gear in the sizes we needed, in stock and ready to go (I literally bought them the day before we left!). So...YMMV, but we were very glad to have them, as well as the water-resistant hiking boots we took (we did outdoor excursions in the ports: white pass & suspension bridge; glacier & whale watching; zip lining). For the weather our week the daytime dress code was jeans and long sleeve shirts/fleece if we were out on deck, jeans and short sleeves if we were staying indoors. I packed enough long sleeve shirts for everyone but myself, so I
had to buy a long sleeve
DCL Alaska tshirt while onboard
The rule for Alaska weather seems to be unpredictability, so my best advice would be to plan to pack layers and to also watch the extended weather forecast and change your packing plans if need be at the last minute. And even if it doesn't rain, unless you live somewhere that is always dry, the rain gear will come in handy in the future
I agree that binoculars were very useful on Tracy Arm day, but we didn't use them other than that.
The one thing I didn't have but wished I did was a waterproof bag/cover for my dSLR camera. Our whale watching excursion was rainy, and I spent a lot of time stressing that the rain was going to ruin my camera (it didn't, but I was obsessive about drying it off).
HTH!
Maureen