One week in Fiji- where to go?

I'm actually going to be in Fiji for two weeks, but staying in a resort for my friends wedding for one of the weeks. I'm planning on coming over a week early to make the most of my trip there, as the chances of getting back to Fiji anytime soon are pretty slim! So I'm hoping for your help- where to go in Fiji with only a week to play with? I'm looking for an area pretty inexpensive (the rest of my trip is costing a small fortune!) but somewhere I can experience the culture and maybe a gorgeous beach thrown in for good measure?