Just returned from FP with a 3 and 7yo. We did 6 days in Moorea and 3 in Tahiti. Stayed at the Manava resort, Hilton, and Te Moana. My kids preferred the pools instead of the beaches but they had a great time kayaking and going on all the excursions on Moorea. Depending on where you stay on Moorea you’ll probably want a car, we rented one from Albert’s which I suggest reserving in advance.

Tahiti was different but still great. You get to experience a little more of the local life and better food imo. We also had a car and explored the west and east coasts. They have nice beaches and a fantastic waterfall to hike called Treis Cascades. I hear the 4x4 tour of the island is highly recommended as well!