Depending on which cruise line you choose, it can be an older crowd. We were young like you and your wife. I used to cruise to the Caribbean for the sun, beaches, and snorkeling. Alaska is about glaciers, mountains, wildlife, and hot drinks.
Choose a cruise that leaves from Vancouver, it usually has better itineraries. If you can see Glacier Bay, that is a treat. Not all lines go there.
Alaska is more laid back. Not a lot of party atmosphere. Excursions can be expensive. I am going to say that we have cruised Alaska once and going again soon. We never get a balcony. The ships that sail Alaska are smaller, than the other places. We like to go and mingle on deck and walk around.