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gabirds
Awards seats between South America and Australia/NZ are very difficult to get, especially in first (just EZE-SYD Buenos Aires to Sydney) and business (EZE-SYD or SCL-AKL Santiago to Aukland or SCL-SYD).
Similar between Australia and South Africa on Qantas (QF), and South Africa and London on British Airways (BA) - are also notoriously hard to get premium awards.
For all these you need to book well ahead (say 11 months) or get lucky. If you are wanting to travel early 2010 then now is the time to book, and with 400,000 miles for 2 that means business not first class (and some programs will still not be enough).
It may be easier to break up the trip into bits and have a mixture of paid and award tickets.