FWIW, when I was there last month and asked at check-in what the RA upgrade SHOULD be on a paid stay (after I was put in a Sapphire from a paid Emerald booking), the guy said "the best available villa is where we put RA's", inferring that if a Diamond Otemanu or End-of-Pontoon was available, they would have put me in it.

Frankly that is more generous than the RA T&Cs require, which I believe promise you nothing at a hotel such as Thalasso, therefore the upgrade rules SHOULD revert back to the Amb 1-category upgrade. That said, they BS'ed me about the availability of better villas (occupancy was about 20% when I was there and somehow they couldn't find me better than a Sapphire)?!?!?! When I called their bluff and booked a Diamond Otemanu room on www.priorityclub.com right away, they called back to my room immediately and said they had found a better "end-of-pontoon" that I had requested and was now available (even though previously they said they were sold out both nights I was there and there was no way I could get a better upgrade ). However their end-of-pontoon offer was Villa #131, which has lots of boat traffic right by it. My wife hates my bickering with the hotels over upgrades, and by that time we were already settled in the Sapphire room, so I just declined their upgrade. It was more for the principle of the matter that I wanted them to know that I knew they were lying to me.

If you really want an upgrade here, you should probably contact them in advance to secure it. I didn't contact them at all, and in fact when I showed up at the Bora Bora airport at 10AM their boat wasn't even expecting me at all. Luckily there was another couple going to Thalasso also, and a second couple was also supposed to be on the flight (and our boat), but they must have missed the flight. Which was somewhat lucky for us as there was only 2 more welcome lei's available at the IC airport booth. So we lucked out and got their welcome leis. ^