Perhaps you know the sense of gloom: after a fantastic holiday in a fabulous destination, you board a plane home and within hours are back in the old routines. How different, when you turn up at Hong Kong airport, to be setting off on a new adventure to Bali or New Zealand or Japan rather than checking in for Heathrow. On a round-the-world trip, great experiences build upon each other, creating memories of cities, beaches, jungles and encounters that will last a lifetime. Your energy levels surge as you anticipate the next destination.
When the first round-the-world tickets were sold in the 1980s, it was because air fares were so high. Anyone with average financial resources who was keen to surf in Hawaii, sip a Singapore Sling or explore the deserts of Arabia needed to pack everything into a single circumnavigation.
For the first decade of the 21st century, fares fell so low (£152 return from London to Boston; £359 to Christchurch in New Zealand) that you could sensibly take in the wonders of the planet in a sequence of discrete trips. But now, with oil at over $100 a barrel, is the ideal time to buy a round-the-world flight. Rising air fares signal a return to the original concept of taking a life-changing circumnavigation. Time to get the globe out of the cupboard and start planning.
First, write down what you are hoping to get out of the trip. A high-intensity tick-list of sights from the Taj to the Sydney Opera House? An orbit of indulgence, from massage in Chiang Mai to feasting in Fiji? Or an urban spin through great "world cities" such as Mumbai, Tokyo and Chicago? Your dream planner should pay due heed to climate. I have frozen in Turkey and been drenched in Denpasar after failing to note the likely temperature and rainfall. The Rough Guide to Weather might make a wise first purchase.
Next, separate your targets into two lists: must-sees and good-to-haves. "A" listers might include the Great Wall of China, the Great Barrier Reef and the Grand Canyon; your "B" wish list could comprise the Pyramids, the Maldives and Honolulu.
Third, you don't have to fly everywhere. Incorporating terrestrial journeys as part of the experience can be much more enriching than stepping aboard yet another plane. So consider a great railway journey through Russia, India or the US; transiting South America by bus; or island-hopping through Indonesia or the Philippines.
The website australiaflightbargains.com has some useful RTW coverage to help with your initial planning, but the final essential is to enlist a specialist to help sift through the options. RTW specialist Haydn Wrath (see panel) explains why human interaction is so valuable.
A good agent will identify the ideal ticket for your planned itinerary – which could well be an off-the-peg deal from one of the three global airline alliances. Oneworld is good for trips that visit Australia, particularly if you plan to include Africa and/or South America.
Star Alliance is the biggest grouping, with the muscle of Lufthansa and United-Continental as well as Singapore Airlines and Air New Zealand. Star's African coverage will be much strengthened when Ethiopian becomes a member, while the impending addition of Avianca-TACA will ensure Latin American supremacy – TAM of Brazil is already a member.
Skyteam is a stylish alliance, with Air France/KLM and Delta at its core. It is weak in the southern hemisphere, but above the Equator the presence of Aeroflot, China Eastern and China Southern make it the natural choice for round-the-world trips that include the world's biggest and most populous countries, Russia and the People's Republic respectively.
"Non-aligned" airlines such as Emirates and Virgin Atlantic can be entwined with other carriers to produce tempting itineraries at affordable fares. Air New Zealand is now the only world airline to offer RTW travel on a single airline – you buy a return ticket from Heathrow to Auckland, routed outbound via Hong Kong and inbound via Los Angeles (the rational way to travel, because of the benefit of the west-to-east jet stream). The airline happens to offer perhaps the best premium economy product in the world. But any RTW itinerary can be gruelling in terms of air miles, so you may consider upgrading for some or all segments. An equally shrewd move is to spend the extra on some extravagant, indulgent places to stay.
A good agent will suggest when and where it is worth pre-booking accommodation, either because of a big event or simply because your flight arrives late at night. They can also sell "ground product" in the shape of excursions from your destination cities.
Once your ideas have crystalised, it's down to the mechanics, starting with travel insurance, which you should take out as soon as you pay for a trip. Note that many policies limit trips to 31 days; round-the-world specialists can offer appropriate insurance.
Getting the right guidebooks is no longer a trade-off between weight and detail, since you can download any Lonely Planet guide to an iPad or Kindle.
For money, many pre-paid cards – the 21st-century version of traveller's cheques – are available, but the Moneycorp Explorer card (moneycorpcard.com) deserves a special mention. You can store 14 different currencies on a single card, with dollars available in six flavours: US, Canadian, Australian, New Zealand, Hong Kong and Singapore. Japanese yen, South African rand and euros are also included in the scheme.
Finally, never forget that the prime reward of global travel is the people you meet.
Why use a travel agent?
"A specialist round-the-world travel agency will put together any route using the best combination of airline alliances, air passes, bolt-on flights and surface sectors – many of which cannot be booked online," says Haydn Wrath of Travel Nation. "They will make suggestions on stopovers and alternatives to your route, unavailable online, which can create enormous savings. They may have travelled to the places you're planning to visit and will make valuable personal recommendations.
"Even if you only want a simple ticket, an agent can advise on how to get the most for your money, eg by telling you about extra free stops and other tricks of the trade.
"With a ticket booked online, if you want to change dates or re-route your itinerary, you may have no choice but to deal direct with one or several airlines. This can be an expensive, complicated and time-consuming process. If you book with an agent they will remember you. They will liaise with the airlines on your behalf and will respond to emails and phone calls. An agent will be available in the event of snow, volcano, strikes. If things go wrong you can be sure an agent will put things right quicker than you could yourself."
Which way around?
For a sense of the possibilities, evaluate these five journeys. Prices, like most things in travel, may vary. These quotes, from Travel Nation, are for departures on 10 January next year. Fares from 16 January are slightly lower, apart from "The Latino".
The following agents are among those worth consulting: Dial-a-Flight (0800 811 4444; dialaflight.com); Round The World Experts (0800 707 6010; roundtheworldexperts.co.uk); RoundTheWorldFlights.com (020-7704 5700;roundtheworld flights.com); Travel Nation (01273 320 580; travel-nation.co.uk); and Trailfinders (0845 050 5886; trailfinders.com). For advice on terrestrial travel, see Seat61.com; the European Rail Timetable is also invaluable if you are including the Continent in your trip.
The classic: London-Bangkok-Singapore-Perth-Sydney-Auckland-Los Angeles-New York-London
The reason this one is so popular? It includes wonderful places, and also offers options for great rail journeys: through South-east Asia, across Australia and as much of America as you might want to see. And because there's plenty of competition, you can expect reasonable fares.
The quickie: London-Dubai-Sydney-Los Angeles-London
Desert, harbour, Disney, home: if that sounds good, then this is a reasonable prospect for a short, long trip (if you see what I mean). You'll be travelling on top airlines (Emirates, Qantas, British Airways or Virgin Atlantic). Many tweaks are possible, eg into Brisbane, out of Sydney; into LA, out from San Francisco.
The northerner: Manchester-Istanbul-Hong Kong-Tokyo-Hawaii-San Francisco-New York-Manchester
A more bespoke itinerary, which is reflected in the price – and you don't get closer than 21 degrees (Honolulu) to the Southern Hemisphere. But for sheer cultural diversity, this one is hard to beat.
The southerner: London-Nairobi-Cape Town-Buenos Aires-Auckland-Sydney-London
Trans-oceanic flights in the Southern Hemisphere are rare – the only link from South Africa to Argentina is twice weekly, on Malaysia Airlines. But if you want to avoid those Gap Year revellers, this is the one for you.
The Latino: London-Rio-Santiago-Easter Island-Tahiti-Auckland-Brisbane-Kuala Lumpur-Delhi-Doha-London
Back where we started: fares to South America are now so high – nudging £1,000 return from London to Santiago – that you might as well make the most of being on the far side of the world by keeping going. Easter Island could be the highlight of your trip, while Qatar Airways offers a different way home from the crowd.