Which island to go to for a very short side trip?

Apologies for the broad question, but I know nothing about the region and would really appreciate some advice to help focus my research.

We're going to be in Australia/New Zealand, have some air miles to use up and figure it would be good to use them to take a short side trip to one of the Pacific Islands.

Our air miles are good for: Cook, Fiji, French Polynesia, New Caledonia, Norfolk, Tonga and Western Samoa.

Money isn't an issue, especially as the flights covered, and we're not budget travellers per se, though we don't spend needlessly on the best of the best if we don't have to.

As we'd only be going for 3-5 days, it would be nice if we went somewhere fairly easily accessible from which we could do different things without too much travel. We're not particularly adventurous, but would be nice to see some interesting sights.

We'd probably check out a beach just to have a look, but not going to hang out there the whole trip. Usually we're city people and pretty laid back on trips wandering around town, though somehow I think that's not the thing to do in these places?

Of these places, we might be most interested in Tahiti and Fiji, only because they're probably the two we've most heard of and might be nice to say we've been. Language wise, we speak French and English.

That's about it really, would appreciate any suggestions to help focus our thinking.

Thanks!

Fiji and Tahiti are surely the best-known islands, but why not try and be a bit more imaginetive?

My vote goes for New Caledonia.
It is comparetively little-visited, but has great scenic beauty to rival anything in the Pacific. Compared to Fiji and Tahiti, it also has the advantage of having one large island that could easily be toured in a short period, and its few off-shore islands, notably the stunningly beautiful Isle of Pines, are easily reached and seen even on a day-trip from Noumea.
Noumea itself is by far the most beautiful city I have seen in the South Pacific, and has the region's best museum in addition to great food.
If you speak French, you will be in better position than most tourists who go to NC, and should find it even more rewarding.

New Caledonia is the closest to Australia, except for Norfolk, which is somewhat different to the others - temperate rather than tropical.

If you speak French and like the city I'd say Papeete would be a logical choice for a short visit. I think you'll find most of the folks in this forum are the off-the-beaten-path adventurous types, myself included.

BTW... I've noticed much of the conversation, in and around the more civilized places, turns to the out-of-the-way places when the subject of holiday destinations comes up. odd isn't it? But maybe I hear what I want to hear...

I think that's because the "adventurous types" are more likely to have spent longer in the region and visited more countries, and then to be more interested in discussing them afterwards.
Folks going for a week-long beach holiday to Fiji, Tahiti or the Cooks tend to drop in once with their questions before going, but rarely keep posting on their holidays afterwards.
But I could hardly call New Caledonia "out of the way" - in fact as OG has pointed out, it is about the closest major Pacific island territory to the main cities of Australia.

I have been in the pacific quite a bit over the years and my favs are vanuatu and the cooks, in particular aitutaki. The winter months in the pacific can be quite windy from the south east so choose carefully which coast you stay on. I mainly dive andgo hikingand travel at budget to mid range level in accommodation. Hiring a scooter in the cook islands is a great way to zip around, and buy your licence when you get there. You need a normal DL from your hhome country. They both drive on the left hand side of the road.

hi, awesome, google whale snorkeling in tonga and go there up from nz, southern winter is the time for this and ive promised myself to do it soon myself, enjoy!