The seas were very calm during our cruise in September apart from one night when it was a bit windy and choppy. However, modern cruise ships have massive stabilisers which minimise the effect of rough seas on the vessel. Also, if you take a cabin in mid-ship as we were advised to do, the rocking is even further minimised.
The selection of tours to book from the ship is almost endless. There is something for everyone. A visit to Pearl Harbour is one of the excursions on offer and I would very highly recommend it.