We've taken 2 Alaskan Cruises with our son who was 8 and 9 at the time of the cruises.
First cruise NCL Sky out of Seattle and the 2nd was the HAL Zaandam out of Vancouver.
On both cruises we had balcony cabins.
In both cruises the kids programs were wonderful and my son had fun at the events he had decided to attend. I assume all lines are equal these days with the kids programs.
The Sky has the Freestyle dining option which I feel is better when traveling with kids. We could eat at any time we wished, never had to wait (dined early), and always sat by a window.
Zaandam we had the late seating and couldn't change and this was inconvenient.
We found that we enjoyed the scenery better from the Vancouver round trip inside passage on the Zaandam. We spent much more time winding thru the islands off of the BC coast. The Seattle departure (Sky) stayed in the more open sea area. However this route is plenty scenic as well.
We had no major ship rocking in either case so if you're worried about sea sickness I don't think that will be a problem (and my son is prone to motion sickness).
Seattle was a more convenient port for us traveling in from Southern California.
I wouldn't hesitate to go with either NCL or HAL again. But I wouldn't rule out other lines either if the pricing/itinerary was right.
Ive been on H.A.L. twice, once in Alaska and once in the Caribbean.I've also cruised N.C.L. through the Baltic Capitals. I am going to Alaska again this summer and to me there is no comparison. H.A.L. is vastly better. Thus we are taking the Amsterdam from Seattle this time because we want to see Sitka. The only way I will ever cruise N.C.L. again is if the price was so good, I couldn't refuse.
H.A.L. cabins are larger
Food is better
Service is far more friendly
Service is better
Maintenance on the ship is far better
Niceties like fresh-squeezed O.J. and free Capuccino
Good Naturalists on H.A.L.
More caring management on H.A.L.
Consistantly H.A.L. ships are reviewed more favorably
I could go on and on......
More important is to consider ports, time in ports, route, glacier. A lot of Seattle departures cruise outside which is something I would not consider. It is only 3+ hours Seattle- Vancouver. All major ships have kids programs that will more than suffice.