We just returned from the S. Pacific and Fiji in December. We spent 4 days at an island resort called Tokoriki and just loved it. It is a 20 minute seaplane ride from the Sheraton Denaru Resort (where we got a few hours sleep from a 3am arrival). We used a travel agent located in Hawaii who got us a terrific price on air, resort, etc. and who I believe handles Blue Lagoon. If you want further info, just advise.

I can't give you any info on time to travel, but we had perfect weather in Nov-Dec.