Definitely Fiji and I would also go for the Yasawas or the Mamanuca islands just south of that. I can't say that I know of anywhere there which is like an Aman, but its still a unique, wonderful place and very friendly people. I found Tahiti to be beautiful, but not so friendly and over commercialised. Stick with the western side for better weather - there is quite a difference. Try Rosie Travel or Hunts Travel - both long standing and reliable companies there of over 40 years.