I would pick four islands for 14 days.
1. The airports there are laid back. It's not like a US airport where you need to be there four hours early and it wastes half your day with surly rent-a-cops, so the travel won't be a big time waster. Just wear the same swim trunks for 12 if you're worried about luggage.
2. If you like good food I understand that Vahine is better than Le Tahaa. I think Le Tahaa is still living off the laurels of hosting Bill gates 15 years ago. I would go to Vahine 100% over Le Tahaa.
3. I'd pick something around Thuatmos definitely and either Moorea or The Brando.
Activity wise, there is a great snorkeling trip with sharks, eels, etc... that all the hotels use (may have been Tinoa that we used). Do that. I really enjoyed the wave runner tour too. Snorkeling around both Le Tahaa and Four Seasons hotels will be a major let down, hence go to Thuatmos. Get a reservation for Villa Mahana ASAP. I'd recommend the FS over StR because it seemed like there were less honeymooners still not financially independent from their parents there. I seriously heard "my dad is paying for this, so I don't care how much this wine costs" several times at the St. Regis and thought, well here's a great start to a soon-to-come-divorce--a lack of financial prudence and independence!
At Le Taha'a play tennis, read and binge watch some show, and going to just two places would be a bit like watching Walker Texas Ranger rather than Breaking Bad.
~enroute to Mars