rta,
Yes, we've been to the main museum, "Museum of Tahiti and Her Islands". I thought it was great, in fact I was going to recommend it to people here, if they are going for the first time, if you are interested in anthropology at all.
But I agree with Sheri that two days is fine. It's the first time I have spent more than a night there, and I am looking forward to it. I want to perhaps rent a car and see Tahiti Iti, maybe catch a bit more of downtown Tahiti when it's not shut up tight, maybe go back to the little oceanside restaurant at the Royal Tahitien Hotel where we stayed last time--they had really great food, and nice laid back ambience.
Or maybe, as Marc says, just relax and laze around the pool drinking Hinano!
I agree that Moorea would be nice--if I thought I could swing it, we would do a pre-cruise there instead, but if we do the back-to-back as we are currently booked right now, we'll be seeing plenty of Moorea--I want to rent a car there too, maybe some of we fellow Pipsters can share!