If you haven't seen my previous post, I am looking into going to one of the smaller islands of Fiji for our honeymoon. It would most likely be one of the Yasawa Group. Matamanoa looks like it would be nice. Our other main concern (along with access/availability of food) is that we would become bored. We love lounging around and relaxing on the beach, but we certainly are not ones to do that for the entire trip. We would snorkel every day, but are looking for other activities as well, i.e. hiking, sightseeing.
While in Bora Bora, we had stayed on the main island for a few days to explore and finished our trip with the remaining days on a private island (motu).