My wife and I just returned from two weeks in Tahiti, with the last 3 nights, 4 days at Le Tahaa. It was, without question, the best of the best and may be one of the nicest places we'll ever stay in our lives.
We were at Moorea and Bora Bora prior to going to Le Tahaa Private Island and we were thrilled that we saved it for last. Any other way and we would have been disappointed in what came next. Also, definitely go with a beach bungalow. Without question. The OWBs are nice, but if you've done them anywhere else, then you've done them at Tahaa (they're just bigger at Le Tahaa, but very poor snorkeling in comparison). With the beach bungalow, you have your own private compound, your own plunge pool, outdoor shower and tub, etc. It is amazing. Enjoy!