I know we can't travel everywhere on every trip, but here are some suggestions if you do stop in Fiji.

(Background - We just did a long Honeymoon in Fiji, NZ, Fiji again, and Hawaii. We skipped Australia this time to go back to Fiji again.) Immediately go to Taveuni Island (the garden island), since you're not a resort/beach type person. The Bouma National Park and the Rainbow Reef are the two biggest attractions. In Bouma, do the Lavena Coastal Walk (hike) and the Tavoro River Waterfalls Hike. There is a shallow river at the end of the coastal walk where you can swim down to two natural rock waterfall slides. (Meet up with other tourists if possible for that part as it can be dangerous.) Then do a snorkeling or scuba trip to the Rainbow Reef with one of the tour operators. We went with Jewel Bubble Divers located just down the street from Bibi's.