We have the same time in Vancouver as you. Although we're doing all our own exploring once we get to AK, I opted for Landsea tours in Vancouver. They pick you up at your hotel, give you a 4 hour tour, and deliver you to the cruise terminal. You can check them out at www.vancouvertours.com
(Grayline also offers tours, but Landsea was recommended to me as being more personal.) Just another option to consider.