I've moved around some pieces of your post in order to link answers.

For AA, here: http://www.aa.com/i18n/disclaimers/f...ward-chart.jsp Note this may well change as the merger with US Airways progresses.

If you were to start and end anywhere in South America the base cost for a DONE5 (vs. a DONE6 if you start in North America) would be $3200 less than starting in NYC. A round trip ticket in business class on AA from NYC to, say, Lima, is under $1500, or you could fly one way on Delta or UA to Bogata for $675. With the Oneworld Explorer you can end anywhere in South America, not just your originating country, so your route would be LIM-SCL-SYD-AKL-KUL-HKG-NRT-DOH-CPT-LHR-DME-HEL-AMS-LHR-MAD-GRU-GIG.

Or, the price of a DONE6 purchased in Japan is US$9471, almost $5000 less than in the USA, but that would require you to rearrange your itinerary, putting your Asia stops ahead of Australia/NZ. Still, with savings like that it might be worth considering.

Changing anything other than dates or specific flights between city pairs (e.g. changing from an AA flight from New York to London to a BA flight) requires the RTW ticket to be re-issued for a flat fee of US$125 or its equivalent in some other currencies. However, the ticket is also re-examined in terms of taxes and fees (changing airports will change the airport and country taxes, for example) and in addition several airlines - Qantas is notorious for this - add "service fees" and may add fuel surcharges which will bump the $125 to a significantly higher number. So it's easily doable, but sometimes with unanticipated consequence$.

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Welcome to this crazy world. Before you drop the big bucks, let me suggest that you put together (in your head or on paper) a 3-year "strategic plan" for air travel. Over the next couple of years, where would you like to go, where do you have to go, and where would you go if price were no object? Not exactly a bucket list, but more than a wish list. Let me explain using a personal example.

My wife and I did our first business-class RTW around ten years ago. We started in Turkey (which at the time was a very "cheap" start point) and traveled first back to the USA, where we used the North America parts of our ticket to travel around the country. A few months later, we traveled to Australia via Hawaii, then to South Africa, then back to Europe and Israel before finishing back in Istanbul. Like you, I was already AA Platinum when I started (my wife too) thus the mileage accumulation was rapid and dramatic. Through the RTW and limited non-RTW travel, we both achieved AA Executive Platinum, giving us lots of perks, particularly eight one-way systemwide upgrades to use on AA flights over the next year.

We had accumulated so many miles that for the next year all our long-distance travel was either "paid" for in miles, or we used inexpensive coach fares and upgraded into business/first with the AA SWUs. We (partially) emptied our mileage balances and fell back to Platinum after a year, but our out-of-pocket travel expenses for that year were a fraction of what we normally budgeted, and every flight was in first or business class.

The next year, we used miles to get to South Africa, which was now cheaper than elsewhere (and we had seriously fallen in love with SA the first time) and started the whole thing again. We used the RTW for premium travel that year (Africa and Asia this time instead of Oz) through which we restored our EXP status, banked umpteen thousand FF miles, and went to places we wanted to go (as well as US trips we had to take for work or family). The following year we burned off the FF miles again, spending very little out of pocket for airfare. The year after that we started the cycle again. It didn't matter that we were starting and ending in South Africa, which is a long way from home in Seattle. A circle has no beginning.

With the RTW tickets costing, say, $6500 each after taxes and fuel fines, and good for 16 flights, we figured we were getting a great deal - around $400 per flight. However, when you add in the "award" flights the following year (for example, we flew from Seattle to Buenos Aires to take a cruise around the Horn, back from Santiago, all in first/business class, among other trips) I figured that in fact our RTW ticket leveraged another 6 or 7 flights using miles the next year, for a total of 22 or 23 J/F segments, so taking the average "cost" down to less than $300. Three hundred bucks for a business class flight from New York to Hong Kong? From Sydney to Johannesburg? Now I know, that's data cherry-picking, but it illustrates the power of these products if one is careful in planning and willing to use the specific rules to one's advantage.

Now this won't work for everyone, or the results might be much less dramatic. But it's worth every minute you think about it. Where would you like to go? Easter Island? Siberia? Patagonia? This year? Next? Done and done. Put it in your plan (along with business trips to Detroit or Dallas if need be) and... engage.