Fiji-worth it?

My wife and I are embarking on an around the world journey in a few months. We've got a couple of options on routes to take.

We'll be going to Thailand, and possibly Indonesia. Our route will either start in Japan or Hawaii. If it's Hawaii, we'd stop in Fiji for a few weeks on the way to N.Z. and then Australia.

Compared to the islands in Thailand and Indonesia (Bali), would skipping Fiji be a mistake? Do the Whitsundays in OZ compare at all?

Depends on what you are looking for.
If all you want is pretty beaches, no need to go further than the Thai islands.
Bali's beaches are poor but the culture and scenery great.

For beaches or even scenery alone, Fiji is hardly worth a detour.
The culture and atmosphere, if you are interested in those, would be different.
And if your RTW ticket already includes AU, Fiji may not cost extra anyway.

It's a good comparison, Thailand and Fiji. They're among the friendliest places I've been, beautiful beaches, a whole tropical rain forest within a city (Suva), which would make Tijuca park in my native Rio de Janeiro a small garden, accessible islands near Nadi. It's cheap, making it "the Thailand of the Pacifiic". I've been there and I'm deffo coming back if I get the chance.

Fiji is well worth it. Having been to Thailand, Whitsundays and Fiji extensively I will say this - all offer a completely different experience and so does. On a pure beach comparison I'd say Fiji wins out because the water straight off the beach is normally clearer and cleaner and certianly warmer than the Whitsundays. Culture wise then Thailand would win out but nothing beats the friendliness of the Fijians especially towards children if you have any. Scenery ? then its a toss up between Whitsundays and Thailand. For night life and any life beyond the beach then Thailand probably wins. However to my mind Thailand sold its soul to the commercialism of tourism about 20 years ago and yet Fiji still maintains a certain innocence. Whitsundays are best done with a boat.