If you can afford Paul G cruise line then go with it, more luxury.
I have been on the Tahitian Princess three times in the past 3 years and like it just fine. It is small, 850 passangers or something like that and I enjoy the smaller ships than the large one, also fewer children on it.
If you can go a few days early do not stay in Papeete, you can take a ferry ride to Moorea and stay there several days, then ferry back to Papeete and hop on your cruise ship. If you stay in Moorea stay at the Sheritan.
You will want to buy pearls in the south pacific, beautiful, expensive pearls. Take your credit card!
You will love the Cook Islands and snorkeling is beautiful, water is warm.