we did an alaska cruise in 2004 and had such a fantastic time! you're going to love it!
as for the photography... we went to the following ports: ketchikan, juneau, and skagway.
in ketchikan, a lot of people went to the logging show, which is supposed to be really fun. we didn't though. we spent time walking around taking pictures of the town and the totem poles. other members of our family did some hiking that day and they loved it. i don't know where they went, but it was somewhere the cruise recommended.
in juneau we took the trolley to the top of the mountain and did some hiking up there. it was an amazing view of the town and they even had a bald eagle in captivity up there. some of our family went to the mendenhall glacier for some hiking this port. the pictures again were so awesome!
we had a stop at tracy arm and saw the glaciers there, which were incredible. we had to be up at 5 am or so, but it was so worth it. be sure to have a super zoom lens if you want some detailed pictures of the glaciers, because you don't get that close to them. we did see a random mountain goat on the hills here, which we thought was hilarious. they had naturalists out this day explaining the types of animals you'd be likely to see in that area.
in skagway some of our family went on the train ride and they said the ride was awesome (it was 80$ pperson). they had some pretty cool pictures that they brought back of the scenery in skagway. in the port area there were lots of brooks with tons and tons of salmon. it was interesting to watch them try to swim upstream and jump out of the water. next to the boat my mom and i got pictures of a mama seal and her baby.
the cruise ship constantly had naturalists on the decks trying to spot any whales or dolphins. we saw one whale one of our days at sea. it was very hard to see however.
be sure to have a zoom lens, a lot of the time you will see animals very very far away. i wish i had a better camera when we went, because i would have many nicer pictures (i guess that's a good reason to go back again! haha.).
hope this helps a little. maybe look into purchasing an alaska book, my dad got one on our cruise and it has a ton of great information in it about each port. we loved alaska and i wouldn't hesitate to go back!
Do you know about things in the typical cruise ports like: 
We took a nature tour in Haines which was for the most part a bust. Weather wasn't the greatest, but we got some cool pictures of some Eagles!!!
