Glad to hear that I've been helpful -- we love cruising with our kids and I like sharing the things I've learned along the way!
Actually we took the NCL Wind from Vancouver to Alaska a few years ago when my daughter was four years old. We had a wonderful time -- everyone on board was very friendly and really enjoyed having the little ones on the ship. If you can afford it, I'd book a cabin with a balcony. That way you can sit out on the balcony and enjoy the beautiful scenery while your baby is inside napping. I always think it's a shame to have to spend many hours a day inside a dark cabin while a baby naps when instead you can be sitting out on your verandah reading, etc.Just make sure when you book it that there will be room to set up the portable crib that the cruise lines provide -- on a recent cruise we didn't have room to set up the crib and open up the pull out couch for my older daughter.
Vancouver is one of my favorite cities in North America -- glad to hear you'll have some time there. It's got great views of the mountains, water, etc.
I hope you decide to go to Alaska with your infant. Just be prepared that vacation will be different from now on that you have a child. But it still can be great!
Feel free to ask any add'l Q's.