You will be bowled over with spectacular Tom. A cruise in Alaska waters is not typical of any other cruise. And if I could tell you anything, it would be contrary to most advice cruisers would give, because most cruisers don't do Alaska.
If you get a choice of cruises, do one that includes Glacier Bay and forgo the Hubbard Glacier routing. If you do, you will cruise right up into Glacier Bay and they will sit for a few hours and you can enjoy lunch on the fantail deck and just take in the beauty...just don't jump out of your chair when the Glacier your parked in front of "calves" a chunk of ice the size of a building, and it sounds like a bomb went off!
One of the best bits of advice I could share, is that you don't stay in your room. If you are looking out at the scenery, you are on deck, not in your room. So an outside room or balcony is a complete waist of money. I can tell you also, that cruise ships are built for tropical climates...and those with balcony rooms complained they were cold! Secondly, if anyone in your party is bothered by motion sickness, an inside room has less roll and pitch along the centerline of the ship, and will be less bothersome when crossing the gulf of Alaska.
We cruised from Seward, a seaport town on the coast away from Anchorage. It is about a 7 hour trip from Achorage to Seward by bus, and is interesting but long. The larger vessels can't come into Anchorage due to 29' tides!!! So Seward is the port. From Seward, we went along the coast and into Prince William Sound. I can't remember the exact timing, but it was beautiful and then during the night, we cruised across the gulf and woke up to the naturalist on board just about to wet himself...because we were in a pod of about 200 Orcas! Yep, right in the middle of them, and they were all sleeping and right on the surface. Then we left and drifted into a big group of humpbacks that were lunge feeding and we had a front row seat for that as well. After the whale adventures, we cruised farther into Glacier Bay and enjoyed the magnificence of that for the day.
From there, we hit the ports of Juneau, Ketchikan, and Skagway. The only tour we did other than walking, was an expensive but worth every penny, two part trip. We did a tour by Twin Otter on floats, up a glacier, across the ice field and down another glacier and back to the airport. About 30 minutes in all, but I shot 4 rolls of film and had tears in my eyes the entire time...incredibly magnificent. If I had had a digital camera (before they were the rave), I would have shot over 1000 pictures. The second part of the tour was a tour through the bald eagle preserve. We floated down a river through the preserve on big white water rafts, but the river was tame. Bear, moose, otter, beaver, and eagles...all present and accounted for. I could write paragraphs about this excursion and the $250 a person that the 2 part trip cost would be a bargain at $500 each.
Tom, the tidewater glaciers are disappearing at alarming rates. Go see them. In the last 80 years, the ice has receded 80 miles in Glacier Bay!!! There will be no more tidewater glaciers in that bay before my lifetime ends. Go now. You will enjoy this trip so much, you won't care that you did it by cruise ship, even if you hate the idea of a cruise. It is the only 7 day or more trip that we have ever done, we are not cruise people. But we would do that one again in a heartbeat. The package that the cruise lines put together for Alaska is very different than the atmosphere for the caribbean. I suspect there are many places that the lines cruise that are similar to Alaska but it isn't the open season party boat that you see in the tropics. We only had one formal night in the dining room, and I rented the clothes for it and my wife bought a dress...she wore only that once and at a wedding. We took warm clothing, but it would have been fine in a medium to light coat or jacket with long sleeves and a good sweater. Do take knitted stocking caps and gloves, you spend a good deal of time outside. It isn't too cold in the towns, just at night and in Glacier Bay and the Sound. If you and your family can get the time to do it, a train tour (adds at least a few days if not 3 or more) up to Denali and Fairbanks from Anchorage and back. We didn't do it, but those we talked to loved that as well. Have a great trip and take loads of pictures...you know where to post them when you get back!