In Juneau, do a helicopter glacier landing. It was the highlight of our whole cruise. Pictures don't capture the beauty. It is expensive, but well woth it even if you give up some other excrsion to be able to afford it.
Went on the Alaska cruise last May. Juneau was beautiful. When the ship pulls in, Juneau is like a picture postcard. We took a bus to the Mendenhall glacier and then did some shopping. The glacier was amazing and the shopping was good.
You might want to look at the other part of the site where you choose a desination instead of the "Shore Excursion" section because I've seen some great tips on Alaska shore excursions in the "Alaska" section and have left some info there myself.
We did the Misty Fjords Flightseeing Tour in Ketchikan. Expensive but truly worth it. Check to see if the Ships Tour stops and lets you get out and walk around on land for 20-30 minutes. The Island Princess Tour only let you step out on the Airplane float to take some pictures. We booked with a charter on or own, save $15 per person, longer tour and they stopped on a Island in the middle of a lake to lest us walk around and take really great pictures. See attachement.
We did the Juneau Mendenhall Glacier Helicopter Tour thru the ship. After touring the glacier by air, we landed and spent about 30 min on the ice. Again, expensive but really worth every penny. We also did the Whale watching tour thru the ship. Awsome. Saw plenty of Humpbacks, seals and bald eagles. It wasn't with Capt Larry but i was impressed all the same.
Check out the reviews in the "Alaska" board. The Photo galerry also has some great Alaska pictures from alot of people.