We’ve researched a lot of different options on Round the World tickets. It’s a great way to control your costs on getting there and back, because after you pay a flat fee you can use as many or as few flights as you want too.
Most of the major airline alliances offer some sort of RTW ticket, and most are based on the number of miles flown. For example: Star Alliance has RTW ticket that allows you to fly up to 39,000 miles, which sounds like a lot, until you try to go from North America, Australia, Asia, Africa, and Europe all in those 39,000 miles and you end up with a number like 41,000 or 43,000.
Because we are trying to hit both Australia and Africa (via Asia) the milage capped programs just aren’t going to work for us. Enter the One World Alliance Explorer ticket. Rather than miles your are capped by zones. We will use 5 zones (N. America, Australia, Asia, Africa & Europe). The price is 4,900 USD plus taxes, etc. and you get up to 20 flights. So it looks like a pretty sweet deal.
We are still learning a lot about it, but this FAQ has been invaluable.
One World Explorer FAQ: http://www.flyertalk.com/forum/showthread.php?t=338667