Ok gurus! Finalised the plan.. see if you think this makes sense: Am first going to fly one way economy (although looks like it's the same price as return on the website) with BA to Mauritius towards end of October. Stay a couple of days, then start an AONE5.

MRU -> LHR -> AMM (Jordan) ->land-> CAI -> LHR -> EZE (Buenos Aires) -> LIM

Then I'm leaving the following sectors open dated:
Lima -> Rio -> Santiago -> Easter Island -> Papeete -> Auckland [not with OW sadly] -> Melbourne -> Sydney -> Tokyo -> Hong Kong -> Karachi -> Bangkok -> Hong Kong -> Johannesburg -> Cape Town -> Finish!!

I can't wait to start now, have completely bored all of my colleagues sitting around me talking about it. I am also considering getting a LAN Explorer pass as I'm going to need more flights in South America - am hoping to pop about between treks without wasting too much time - do you think this is better than just paying for flights as and when you need them? I'm guessing in Asia this will be easier to do with low-cost carriers like Air Asia (shortest miniskirts I've ever seen air-hostesses wear, heh).

One other question - would the BA Travel Shop in Mauritius be able to ticket my flight from UK to Mauritius? I checked online and it's substantially cheaper if you "claim" to be in Mauritius.

Thanks for all your help everyone..