17 airlines offer a certain kind of layover that sometimes comes with lavish perks like a free hotel room or city tours - here's how to master the stopover

While China requires a visa for most visitors, those passing through China en route to a third country can stay in the country on a free transit visa for up to 72 hours.

Air China offers a transit program for those taking advantage of the quasi-loophole to gain access to the country and provides one-night hotel accommodation for those passing through Beijing, Chengdu, Shanghai, Hangzhou, Tianjin, and Chongqing, making it one of the most extensive programs in terms of a number of cities served.

Though Avianca is the only South American airline to offer a stopover program, its maximum duration is limited to 24 hours and is only available to those passing through Bogota, Colombia. One of the northernmost South American capitals, Bogota is geographically ideal for those transiting between North America and its southern neighbor.

Once booked, the airline offers recommendations on tours depending on the stopover length, with the minimum stopover time being eight hours.

One of the smallest European airlines to offer a stopover program, Brussels Airlines allows passengers transiting through its main base in Brussels to make a stop in the country for one to five days. The de facto capital of the European Union, Brussels is essentially the capital of Europe with neighboring capital cities such as Paris, London, Amsterdam, and Luxembourg only a short hop away.

With a limited number of routes to the US and Asia, the primary market for the stopover program is Americans and Europeans heading to Africa and vice versa. Brussels Airlines maintains a strong route network to Africa.

Though not wide publicized or streamlined as other airlines, Emirates does offer a stopover program, following suit with fellow Emirati carrier Etihad Airways. Travelers passing through Dubai, one of the Middle East's main transit hubs, can build in a stopover by booking a multi-city ticket and then contacting Emirates to help make arrangements for accommodations and visas.

As Dubai is one of the most opulent cities in the world, its popularity and tourism rate has grown exponentially in recent years. Emirates similarly offers one of the world's most luxurious in-flight experiences for its premium passengers, with its Airbus A380 aircraft offering in-flight showers for first-class passengers.

Etihad Airways offers travelers transiting through its hub in Abu Dhabi the option to stay over free of charge for two nights, with the airline even picking up the hotel tab. For those seeking to stay longer, the airline offers discounted rates at local hotels and will even pay for an entire night if a stay of four nights is booked.

Abu Dhabi is one of three global connection hubs in the Middle East along with Doha and Dubai thanks to Etihad, ideal for those flying from North America and Europe to destinations in the Middle East, Africa, Asia, and vice versa. For those not looking to stay the night, the airport offers shuttles to top attractions such as the Louvre Abu Dhabi.

Ethiopian Airlines offers passengers flying through its main hub in Addis Ababa the opportunity to stopover if their layover is between eight and 24 hours.

Though not a proper stopover program in terms of an emphasis on tourism, the airline will arrange a complimentary hotel stay, transit visa, and airport transfer.

Finnish flag carrier Finnair offers a stopover program through its main hub in Helsinki for passengers flying through the Nordic country. As one of the northern and easternmost European capitals, Helsinki nearly sits under the flight path for aircraft heading between Europe and Asia, making it an ideal transit city.

Finnair's program allows passengers to spend up to five days in the Nordic city free of charge on either the outbound or return journey. With Finnair's route network heavily favoring Asian destinations, the program is ideal for travelers heading to and from that region.

As the airline is also expanding in the Americas to cities such as Los Angeles in addition to existing service to New York, San Francisco, Miami, and Chicago, however, Americans heading to Europe or Asia via Helsinki can take part as well.

Following suit with its Portuguese neighbor, Spanish airline Iberia recently introduced a stopover program centered around its hub in Madrid. The program allows visitors to spend up to six nights in the Spanish capital before continuing onward.

Iberia primarily serves North America and South America in addition to its short-and-medium-haul European and North African destinations, making it ideal for travelers in the Americas heading to Europe and vice versa.

Through its strategic positioning in the North Atlantic Ocean, Iceland is a nearly a half-way point between Europe and North America and an ideal transit hub. Passengers fly up from either North America or Europe and then connect to a secondary flight that descends back to the lower latitudes.

One of the more generous stopover programs, Icelandair allows passengers to stay in the island nation for up to seven days free of charge. The program was copied by low-cost competitor WOW air and spurred a tourism boom in Iceland, a country known for its natural wonders.

One of the lesser-known Middle Eastern stopover programs, Oman Air offers passengers traveling through Muscat to stay for up to three nights, with the airline picking up the tab for one night if at least two nights are booked. With no current service to the Americas, Oman Air primarily serves passengers traveling between Europe, Asia, Africa, and the Middle East.

The airline prides itself on serving traffic originating and departing in the country, but does offer onward connections that take advantage of its strategic location on the Arabian Peninsula.

As part of its country's push for more tourism, Qatar Airways offers stopovers of up to four nights for those traveling through its main hub of Doha. Another global connection hub in the Middle East, Doha has been increasing in prominence thanks to Qatar Airways, one of the most highly-rated premium airlines in the industry.

Though hotel stays are not part of the program, the airline offers discounted rates as low as $28 for a night in a five-star hotel. For those with shorter stays, the airline offers city tours at discounted rates, as well as desert excursions.

Royal Jordanian offers a stopover program for those passing through its main hub in Amman, the capital city of the Middle Eastern kingdom. The airline offers tour programs to nearby sights and attractions including the Dead Sea and Petra.

For shorter stays of less than 24 hours, Royal Jordanian will also provide a complimentary hotel stay in Amman.

Singapore Airlines offers passengers traveling through its namesake city-state with layovers of over 24 hours to purchase discounted stopover packages. The most basic package offers a hotel stay and one-way airport transfer while the more involved packages feature free access to attractions, local discounts, and additional nights of hotel stay.

Swiss International Air Lines is one of the few European airlines to offer a stopover program for two cities in its country, Zurich and Geneva, where the airline maintains international hubs. The program allows flyers on the Swiss flag carrier to add a stop in the country between two to five days in duration before continuing onward.

As a central European country, Switzerland is primed for connections between Europe and Asia, South America, North America, and Africa. The program also allows for tour packages, hotel stays, and transportation to be booked through the airline.

Under new leadership from airline magnate David Neeleman, TAP Air Portugal introduced a stopover program for its two hub airports, Lisbon and Porto. The program allows for a stay of up to five days in either before continuing on to a final destination.

TAP Air Portugal primarily services cities in North America, South America, Europe, and Africa, making a stopover ideal for passengers heading between those continents. With Lisbon and Porto's geographic location on the extreme west coast of Europe, they're the closest cities from North America and South America and ideal for stopovers.

Turkish Airlines offers a stopover program for passengers flying through Istanbul, the crossroads of the world where east meets west.

The airline also offers free hotel stays for passengers, with economy class passengers getting a complimentary one night stay and business class passengers receiving a complimentary two-night stay.