I was the guy asking for the other sanity check :-) it was quite useful. i decided to go back straight to the drawing board with a much simplified itinerary, as I was doing a lot of backtracking too (including over the land).

As suggested, Mileage Monkey (linked above) is a great place to start. I like in particular, the tool which shows you all ONE eligible flights out of a particular city. This can alternatively be done using the 'interactive map' on the Oneworld.com site. I find that both of these, in combination with the downloadable oneworld planner, are quite useful, and might help you avoid backtracking situations.

For example, you could do things such as, on the way back from Beijing stop in Singapore/Bangkok rather than HKG again. I think it's possible to get DEL flights from there. Or atleast till Mumbai, and then look at internal LCCs in India.

Another recommendation is that you can use a lot more land sectors, for example in the hong kong-beijing thing is not hard by train. A tough option is to do Panama to Lima overland, but folks have concerns about crossing Columbia by land.

In south america, I'd recommend SCL-IPC-SCL too.