Here is route map for Air Pacific. Fiji is sure out in the middle of nowhere. For pure distance, flying to Hawaii would be shortest. For cost, I don't know. Tokyo works and so does Oz or NZ.

I am facing same problem. Skyteam (Delta et al) doesn't fly to Cambodia. Therefore, I have had to add a Vietnam Airlines leg to Saigon to connect with my Korean Air flight that I am using ff miles for.

Good luck!

Edited to add:

I punched in a date in a couple of weeks. Only way to get back to Singapore is via Oz or NZ. Cheapest for one way was $775 via Auckland on Air New Zealand/Mt Cook. This is not necessarily a representative price since this is for a ticket soon.