Australia, New Zealand & the South Pacific - Fiji or Cook Islands?

This summer for my Australia trip, I want to take a week trip to either Cook Islands or Fiji. Problem is, the Fiji flights that are available for award travel do not make the most out of the time. I would have to layover in AKL at least 1way if not both. Cook Islands on the other hand are just fine.
I also don't know if a week is too much in the Cook Islands. My main purpose is to dive, though a day seeing local sites would be nice. RAR isn't big, so day is plenty.

Routing wise, I would do
if RAR: SYD HBA AYQ PER RAR MEL
if NAN: SYD HBA NAN PER MEL

I would lose either PER or AYQ in the NAN routing. If NAN is worth while to see, then its fine. If not, then RAR would be better. What should I do?

Can't speak to diving around the Cooks but believe you'll find dive operations on Rarotonga and Aitutaki. I've been there a few times and enjoy the Cooks uncrowded, self catered nature.

A few web sights you may want to look at are southpacific.org (http://www.southpacific.org/) and www.ck (http://www.ck/)

I'll have a look. Diving seems to be there but the quality doesn't seem to be the same as Fiji

Aitutaki is probably one of the most beautiful islands in the South Pacific easily beating out (IMHO) anything in Fiji. Diving is good and they use NZ dollars so if you're visiting NZ as well then you don't need to change currencies again.

The Pacific Resort and Rarotongan Beach Resort both have hotels both on Rarotonga and on Aitutaki and do packages for staying at both (eg 4 nights in Raro, 3 in Aitutaki) - makes them good value.

I was able to get a C award on NZ to NAN for a total of 6 days/5nights. Not I got to find places there for diving and staying. Any recommendations? I was thinking (as I get into NAN about 10AM) basically fly out to a resort for maybe 4 days and head back into NAN for a night or so to see around the town and local area unless there are dive companies that if I stayed for instance in the Westin NAN they can pick me up there and drive me to the docks for a all day excursion. RAR did not just at the end timing work out.

There are a lot of resorts in Fiji which offer diving. I have been to Matangi north of the main island which caters to divers. It is a lovely very small resort. Close by on another island is the Cousteau Resort. Although I haven't been there I think there might be a few more activities close by if you want to experience other things besides diving. I think you were wise to choose Fiji rather than the Cook Islands for diving. Not to say that the Cook Islands are not wonderful in their own way. Do a search on www.divefiji.com or www.fijidiving.com.