I support all the comments on the beauty of the island and friendliness of the people. We stayed at the Regent of Fiji (now Sheraton Royal Denarau Resort) as a stopover coming back from NZ. Excellent wine list and high standard of cuisine in the restaurants (although this was back in 1992). Given the likely cost of the flight, there's really not much point in skimping on the hotel accommodation.
FWIW our route back was ANZ (-HNL-LAX) and BA (LAX-LHR). Going east (from UK) is theoretically a slightly shorter route, but almost all scheduled flights go via HNL/LAX or Australasia (the only eastbound routing seems to be via Tokyo). You could get a round-the-world ticket, which might be cheaper and would allow for interesting stops on the way (if you can afford the time
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Only negatives are that it's a long way to go - 24 hour flight from UK with at least one plane change - and in the rainy season (Nov-Apr) you can pretty much guarantee a tropical downpour for an hour or so every afternoon.