Bula!
If you are staying in Denarau, you can go to Sigatoka, do highlands treks including Sigatoka (seen-guh-TOKE-uh), you can kayak the Navua or Wainikoroiluva (just call it 'luva - everyone will understand) rivers, visit First Landing for lunch and views (where the first Fijians arrived) and visit the orchid plantation at Garden of the Sleeping Giant the same day as well as a Fijian (as opposed to Indo-Fijian) village. (Rivers Fiji and other suppliers offer the kayak trips). None of it is really far.
And though I can't recall the name, there's a small steakhouse near the water (not beach / Pacific, but toward the marina) where I have had pretty good steaks - maybe, iirc, the cattle are descended from the boat that wrecked en route from Argentina to Australia with breeder cattle, which the people kept along with the drover, but ate the sailors? (Yes, the Fijians practiced cannibalism and some are proud of it - they are still warriors and can be found in places where there are wars, e.g wearing blue helmets for the U.N. in some lead-filled parts of the Middle East.)
You can also visit Nadi (pronounced NAHN-dee) and see a very few sights - the colorful Sri Siva Subramaniya temple, check for souvenirs of all kinds at Jack's (some very nice ones - "Jack" is actually Mr. Mr. Jekishan Khatri). You can get your VAT claoim forms for the airport, and the wood items are treated - no US or Australian customs hassles for wooden items like war clubs or that huge tanoa you can use for mixing up your own kava at home.
I always have dinner in Nadi (sometimes check in very early for my flight at the airport and go back to town) at the very nice Chefs The Restaurant (this is NOT the same as Chef's The Edge, and they are both owned by the same person who owns Jack's and are both nearby) for dinner.
The times I have been there the food and service have been excellent, and once or twice when other diver friends and I have dined the friendly staff lined up and sang "Isa Lei" the Fijian farewell song) to us.
Note: the Fijian sun is
very strong - use some of the best sunscreen, perhaps SPF 50, and apply it several times. And don't forget some "seqa la leqa" time (SENN-guh lah LENN-guh = take it easy).