SE Asia, Fiji, Kiribati. Flights sorted, help me fill in the bits between?

Now then, I'm back after some re-planning etc etc.

I've booked my flights so here's the skinny (ignoring the bit where I'm in Thailand and Laos):

Arrive Fiji 19th Aug early morning

I want to transfer immediately to Beachcomber (or some other (better?) party resort) where I'll spend the weekend.

I'd like to to explore the Mamanucas/Yasawas for at least week to ten days

and to spend the same amount of time exploring the mainland. Perhaps do the Sigtoka river trail, visit some villages etc.

I'll be departing Nadi for Tarawa on the 8th Sept and spending until the 29th Sep around Kiribati.
I'd like to include Tarawa, Abiang, and Marakei in my time there.

On the 29th Sept I go back to Nadi, Fiji from Tarawa, two nights in Fiji before flying back to the UK from Nadi on the 1st Oct.

So, if anyone has any advice on where's good/good to avoid in the places I've mentioned, especially including how I can best spend 2 nights in Fiji whilst I'm kicking my heels waiting to get back to the UK, then it'll be greatly appreciated.

I'm looking for a nice mix of touristy stuff and striking out on my own and doing some "non organised" adventuring.

Cheers
James

The only Q I can see here is "how I can best spend 2 nights in Fiji whilst I'm kicking my heels waiting to get back to the UK" and the answer to that is easy enough:
Spend those last days in Nadi doing your shopping for souvenirs. You can always visit nearby Lautoka if you want someplace else, but that's about as far as you could go in 2 days.

Personally I would have allowed more time for Fiji and less for Kiribati, as Fiji is a much bigger and more diverse country. 2 weeks would be plenty of time to see Tarawa, Marakei and Abiang.

I've also been looking at Awesome Adventures' Beach Bum package which will allow me to stay at the Beachcomber and Manta Ray for 2 nights each.

Has anyone been on any of these packages before? Any recommendations etc?

Thanks again