I was in Fiji in June last year & two other times previously. Actually I was there last year the same time as Daniel but staying at different resorts. As Daniel stated , the resorts are so nice , it's a chance to just relax , eat , drink , swim etc.
We stayed at The Warwick Resort . It was fantastic , better than the Naviti but not as good as The Fijian Resort (places I've stayed at before). Definitely worth paying for the "all inclusive" deal . You get given a wrist tag that allows you to eat & drink whatever/whenever.
We did 1 day tour , which I would recommend . It was called the Fijian Experience. Went by long boat to a Fijian Village for a tour & Kava ceremony , then much further down the river ( very scenic ) to some spectactular waterfalls , which we were able to climb & swim under. The river had rapids that we travelled over & apparantly was the same river that one of the Anaconda movies was filmed at. It was a fantastic day trip. Ask about it at your hotel.
The only downside of my trip last year was following the match progress between Manly/Penrith at Penrith Stadium on the internet. We lost a match that we should have won.
I'm sure you'll have a great time Byso , but as mentioned you'll find yourself spending plenty of quality time at your resort enjoying the sunny weather by the pool.