The dive places you can choose from :
- don't miss Bligh Waters, north of Viti Levu easy to get from Nadi airport, probably the best of Fiji has to offer in terms of color and fishlife. Volivoli should be on a budget. This is the place you NEED to go diving for 4-5 days.
- Taveuni island, needs a plane to go, nice corals, mantas, the most expensive of the Fiji resorts.
- Eastern Viti Levu, off Suva, Naigani island is supposed to be one of the best kept secrets for diving Fiji, not been though. Will certainly be my next Fiji destination.
- Kadavu for authentic Fiji, needs a plane too or a ferry ride from Suva. Dive the Great Astrolabe reef, lush corals, though I didn't find that much fishlife, fantastic people and rural life. Quite cheap for lodging, if you want to experience life like a fijian, this is the place, their kava is a kneebreaker. 
Some people also say Beqa lagoon, (not been impressed with the corals or anything) or South Viti Levu for tiger/bull sharks feeding dives.