Jeana,
You will absolutely love it!!! I posted a review about the trip. A few other things I didn't post....The ports are big tourist traps with more jewelry stores than you can imagine. If you get away from the dock, you can find a more relaxed atmosphere where the locals shop. Ketchikan, Skagway, and Juneau downtown areas are very easy to walk.
We had a balcony room on deck 7. Take binoculars!! and also take them on any excursions. I have Tasco 7x50 and they were just fine. You don't need to invest big bucks. The onboard duty free shops are fairly cheap although the only thing I bought there was booze. My wife bought smoked salmon onboard and we did not find it cheaper in any of the ports or inland. That surprised me. At port disembarkations the lines to get off the ship were usually long. Save yourself the stress and wait 15-30 minutes unless you have an excursion. Be back on board when they say because they leave on time!!
I have a tux and took it but maybe 1/3 of the people had them on formal night. I was the only one at our table with one and I had no problem with those who did not wear one. All other times dress casually even if eating in the dining room for any meal.
Take layers. I am warm-blooded and often wore a sport jacket and was fine on deck and in port unless it was raining. Inland, I normally wore a slightly heavier camping-type jacket and again was fine. The coldest temp I saw was 42 one morning in Fairbanks. My wife put on her gloves a time or two. Temps were typically in the 50s and 60s during the day. Coming from eastern time, we were always awake at 4AM and it was light so an alarm clock wasn't necessary but we took one anyway.
Once we hit the land tour portion the food prices were quite high. I just finished breakfast here in the UP and for three of us it was $11. Breakfast inland will typically run that much for one person. Muster drill wasn't as bad as everybody says but they do make men stand in the back of the deck and women and children nearer the lifeboats. What a sexist practice, eh. Everybody had their cameras taking pictures and took it lightly, except the crew..they were serious about it and that's fine.
The best tip is to relax and be amazed at how time seems to stand still. Three days into the cruise we swore we had left Vancouver a week ago and by the time we hit land it seemed like a month ago since we saw and did so many memorable things. Definitely archive the trip with pictures or video. I wish I had video at Hubbard to record the sounds and the calving.