Now may just be the time to take a sabbatical—or, heck, quit your job altogether—and buy a round-the-world airline ticket. Airfare consolidators and discount travel specialists can create cheaper-than-ever globe-spanning itineraries by scouring the industry for closeout prices. And U.S. airlines have started teaming up with foreign carriers to offer great RTW deals.

The lowest fares restrict travel to the Northern Hemisphere—and originate in New York, Los Angeles, or San Francisco—so we asked five U.S. companies that specialize in RTW packages to show us their best deals on tickets with stops in Hong Kong, Bangkok, Delhi, and London. These tickets are loaded with restrictions: With most, you'll need to travel either east-to-west or vice versa without backtracking and complete your trip within a year. But the $3,000 or so you'll save might be well worth the trouble.  —Philip Armour