Ever dream of jetting to one far off place after another? An Around-the-World (ATW) ticket may be the answer. In conjunction with the World Traveler segment I've been asked to comment on this type of ticketing arrangement.
There are three airline alliances which market the ATW ticket: Sky Team, OneWorld and Star Alliance. Each have remarkably similar restrictions and prices (covered below) so the most important factors in selecting an alliance is where you want to go and which alliance flies there. With so many airlines and so many destinations its impossible to discuss the best option in abstract terms. You'll need to think about the places you want to go and do some research. Star Alliance has the largest network with the most member airlines, but doesn't cover all the continents equally. Star was lacking in South American presence until the recent addition of TAM-Brazil but if South America is one of your primary destinations (and you'd like to visit a lot of it) you might be better off on a ticket with OneWorld whose members include American Airlines (good connectivity to and from the States) and LAN which includes subsidiaries in Chile, Peru and Argentina and can get you almost anywhere in South America.
Prices are usually significantly better than the sum of the cost of a slew of one-way tickets. The largest economy tickets allow up to 39,000 flight miles on 16 separate flights and run between $6,000 and $7,000. It seems like a lot up front but consider how much you'd spend on just 3 or 4 one way, intercontinental tickets. All good things come with restrictions, however, and in this case paying attention to them can make or break a trip.
All three alliances have nearly the same restrictions but some define differently where travel zones begin and end so be sure to read up on whichever you're using. In general travel must begin and end in the same country but not in the same city (i.e. depart from New York and end your trip in LA). Also you must cross the Atlantic and Pacific oceans exactly once and in the same direction (i.e. if you fly from New York to Paris, you must cross the Pacific from Asia/Australia to the US or Canada). Additionally you can only cross into each 'zone' once and must continually move in the same eastward or westward direction. The most generous and loosely defined zoning marks the world into three sections: The Americas (including North and South), EMEA (Europe, Middle East, Africa) and Asia Pacific (everything else including Australia). Many tickets divide the world into five or six parts separating Africa, South America and the South Pacific into their own regions, but you get the idea. One you have crossed into a zone you are free to move about as you like as long as you don't exceed maximum number of flights on your ticket. Backtracking is permitted here, only within the current zone. When you move to a new zone it must be in the established direction of travel.
All of these tickets, if booked online, require you to choose your dates and flights for the entire trip up front. On the other hand if you book the trip through a reservation agent at one of the member airlines you're usually allowed to reserve just your first flight and leave the remainder open to use as you please over the course of a year. Keep in mind though that as you use up flights and mileage the ticket will become more restrictive because you'll need to have enough of both left to get to your home country. You cannot simply use all the miles and see where you end up (presumably buying your own way from there). You must end your trip in the country of origin. For this reason its probably a good idea to have some notion of (at the very least) where you'll be starting and ending, and how many miles and flights you'll need to get between those places and home.
Finally note that ATW tickets usually book into a specific fare class which has the potential to sell out. Airlines can also restrict specific flights from being used by ATW travelers. This means that even though an alliance carrier flies from point A to point B, you might not be able to get a ticket on that particular flight. Using the online booking tool will help identify which flights are available to ATW travelers. Most flights will be bookable but its worth keeping this in mind, especially if you're going to reserve your flights in the midst of your trip, as you go along.
ATW tickets can be a flexible and cost effective option. But like all things, you give up complete flexibility for a better price. If you can stand a bit of planning this might be the option for you. If you need to roam the globe free of encumbrances, look elsewhere.