As mentioned before, a scooter's the way to go. So rent one from a local, hop on and make your first stop the Jus de Fruits de Moorea factory where you can sample the fresh pineapple, guava, passion fruit and mango blends, as well as the "Tahiti Drink," juices and a little dash of alcohol. Don't be suckered by their giant gift warehouse, as you can buy the juices at any local supermarche and enjoy them lots of places in Tahiti.
Keep heading down the road and you'll hit a small paved road that eventually climbs a steep crater wall and proceeds to the island's most scenic spot: Belvedere Lookout. Make sure the gas tank's full and the brakes work, and you'll get all the way to the top where there are unobstructed views of Cook's and Opunohu Bay, as well as the verdant Mt. Rotui. Take lots of pictures but avoid bringing lunch, as wild roosters abound and are quite friendly.
On the way back to Cook's Bay, pull over and check out St. Joseph's Catholic Church which has a beautiful, handcrafted mother-of-pearl altar and very cool wall mural. Another secret? Pop around the back of the church for gorgeous, private views of the bay.