Thanks for the interesting and balanced review of your trip.
I have to say I'm somewhat surprised Club HAL was so good. They don't get all that much practice on HAL ships. With "the older demographic" HAL draws I'm not surprised that some passengers would view the kids as an "intrusion".... even if they never heard a peeps from them.
What you mentioned being the most important thing about you not returning to the line.. the motion.... wasn't/isn't due to the size of the ship. It's a falacy to believe that the larger ship, the less motion you'll feel. Big ships don't ride any better than smaller ships.
It's all just a matter of mother nature's oceans, winds, and currents, etc. All of the modern cruise ships have stabilizers, but if conditions are "wrong" you'll find the motion or lack thereof pretty similar.