I did Quantum last year in Alaska. We didn't travel with kids or teens, but some pros and cons of the ship specifically I experienced:
Pros:
- Lots of activities. Not sure what was happening in the kids clubs, but outside of it there was the Northstar, the skydiving simulator, the Flowrider, bumper cars, and a rock wall, plus lots of trivia games.
- Three pools, two of which were covered, which was great. The adult only solarium was huge and beautiful, and depending on the age of your teen and their maturity level they should be able to enjoy this as well. Even having an enclosed top deck was nice so you can sit "outside" while staying warm.
Cons:
- A lot of those activities I mentioned above were outside, so if it's cold, rainy, and windy (which it was on our sea days when you would be most likely to do these activities) it might be canceled, or just not be a fun experience.
- The Quantum has kind of a weird layout, and because of it it felt really crowded at times. For example, trivia was in a bar that was small and was also a walk through area, so it was hard to claim a seat and people were always moving through the area. The covered pools were great, but since the ship is large it was also hard to get a seat in there. We felt like we spent a large part of the day just looking for places to sit and hang out.
- The food was really hit or miss.
- Barely anything felt "Alaska". There was one shop they set up selling Alaska merch, but there were no guest speakers, Alaska specific events, or special items on the menu that reflected where we were. We're trying Princess this year for Alaska because I heard they are great for Alaska and incorporate the location into the cruise, if that makes any sense.
- Quantum (and Ovation) are big ships, and they can't sail the inside passage, so our sea days were true sea days with nothing to look at besides water.
- This year we are sailing out of Vancouver instead of Seattle, and I think we'll enjoy that more. Seattle round trip ships have to stop in Canada, which is usually Victoria. It was a lovely town, but we only got to spend like four hours there in the evening. It feels like the ships just "tag" in to meet the legal requirements of visiting Canada. Thus, it feels like a waste of a day. On our seven night cruise we only spend three of them actually in Alaska. I would look at the itineraries and try to find one that maximizes your time in Alaska, if at all possible. The one plus side of sailing Seattle is that if you are in the US it's usually easier to fly there than Vancouver.