Definitely head over to Moorea. I can't help you with OWB suggestions, but you will definitely want to spend your time in Moorea over Tahiti. Beaches and snorkelling are spectacular in Moorea, not to mention the mountainous scenery. Lots of restaurant options too.
Plan to spend a bit of time in Tahiti, I would say the day of embarkation would be fine just to walk around Papeete and see the big market. You could also do a 4x4 tour of the interior of Tahiti (1/2 day) if you wanted, but you can do a 4x4 or ATV tour in Moorea and get amazing views of the mountains AND lagoon (Tahiti's lagoon is not like Moorea's).
Have a wonderful time! My husband and I have done the 10-day Princess Cruise (just around FP, not to Hawaii) twice and loved it. Let me know if you have any questions!