We aren't planning on going until October, and won't be in Chile until Jan/Feb next year so I'm hoping things will be a bit better down there by then.

After having another look at our plans we decided that San Francisco might be pushing the price of our ticket up, so we have re-thought and simplified, and come up with;

UK - Mexico (26/10/10)
Mexico - Lima (25/11/10)
Lima - Santiago OVERLAND
Santiago - Auckland (05/03/11)
Auckland - Christchurch / Queenstown OVERLAND
Christchurch / Queenstown - Sydney (09/04/11)
Sydney - UK

A seperate return ticket from UK to Bangkok would be added on top of this. I think that this would probably be a cheaper option than trying to start and finish in Bangkok.

We are looking for the cheapest way to visit South America and Australia / New Zealand, so if changing where we arrive and depart from has an effect on the price, we are flexible. Also if leaving out Mexico has a big effect on price, we can always book a seperate ticket for that too.

I'm not sure how this will effect everything, but it's worth a try.