Stopovers Provide Trip Options : Airlines: There’s a way for passengers heading overseas to visit other cities on their scheduled route, often at no extra cost. A few restrictions apply.

Want to visit Fiji and Honolulu on your way to Australia? Add stays in Prague and Budapest after leaving Moscow? Or see Panama City or Lima en route to Rio de Janeiro?

These extra destinations on a travel itinerary, called stopovers, are often available at little or no cost beyond the price of the original round-trip ticket, and are especially popular when flying overseas. You just have to ask.

By way of definition, on international flights a stopover occurs when your stay in a particular place is longer than 24 hours. If you continue on to your next destination within 24 hours, it is considered merely a connecting flight. (On domestic flights, a stopover occurs if the stay in one city is longer than four hours.)

The availability of stopovers depends on factors such as the time of year and day of week flown, whether the fare is purchased at a regular rate or part of a promotional deal (expect more restrictions in the latter case) and the total mileage permitted by the airline on that particular route.

Don’t expect to find the best stopover deals during peak tourist periods.

Since stopover rights are not always promoted, or well known, it’s a good idea to check out options with a travel agent.

One strategy, in lieu of booking a specific stopover, is to take advantage of a regular connection, i.e., book a flight that is scheduled to arrive at a city too late to catch the airline’s next flight to your destination. In such cases, some airlines will provide complimentary overnight accommodations. However, this policy often depends on the class of service flown. First- and business-class passengers are more likely to receive such perks.

It’s also possible to use other airlines for some stopover flights. For example, with TWA’s regular coach fare from Los Angeles to Rome, travelers are allowed two stopovers in each direction--one each in the United States and Europe. That means an itinerary could read: LAX-New York-Paris-Rome-Geneva-New York-LAX.

“The domestic and transatlantic flights would have to be on TWA, but the Paris-Rome and Rome-Geneva flights could be on other airlines,” said Jan Wood, Los Angeles regional sales manager for TWA.

The mileage on this itinerary amounts to 6,757 miles, well within the mileage limit of 7,608 miles set by TWA for this route.

Another example: If you were booked on a full-fare LAX-Frankfurt-Moscow flight on Lufthansa, you would be entitled to free stopovers in each direction, within the mileage allowed. Accordingly, you could stop in Budapest on the way, then visit Prague on your return to Frankfurt. And the Budapest-Moscow, Moscow-Prague flights could be on airlines other than Lufthansa.

On Lufthansa’s “Excursion Three Month Fare,” travelers are permitted two stopovers, one each way, with each stopover costing $25. However, even with these extra costs, the round-trip fare plus two stopovers would still amount to a savings over the regular fare. Restrictions include a minimum 10-day stay, and completion of all travel within three months.

In the South Pacific, Singapore Airlines offers unlimited stopovers, depending on mileage, with full-fare purchases. On the carrier’s “Super Easy Fare,” additional stopovers cost $50 each. Singapore also has an “Easy Fare” that permits two free stopovers, plus optional use of another airline.

You could fly LAX-Honolulu-Singapore-Bangkok on Singapore Airlines, then use another airline to get from Bangkok to Hong Kong. Your return flight from Hong Kong to LAX would again be on Singapore Airlines.

Air New Zealand offers unlimited stopovers for all classes on its regular fares to the South Pacific. You could, for example, stop off in Honolulu, Rarotonga in the Cook Islands, Nadi in the Fiji Islands and Papeete in Tahiti.

Stopover rights vary with Air New Zealand’s promotional fares, ranging from four free stopovers on the excursion fare to three free stopovers with the APEX fare.

Though its flights from LAX to Tokyo are nonstop, Japan Air Lines allows first-class and business-class passengers to first fly to Honolulu on other airlines at no extra charge. In effect, travelers have a free stopover in Hawaii before picking up their JAL flight from Hawaii to Tokyo. Economy-fare passengers can also take advantage of this stopover option, for an extra $30.

For South America, Varig offers unlimited stopovers on its regular fares. Free stopovers, for example, are available at Lima or Panama City--depending on the day of week--on the carrier’s one-stop flights from LAX to Rio de Janeiro. One routing could be LAX-Lima-Rio de Janeiro-Panama City-LAX.

“You can also use other carriers for some segments,” said Karen Dawson, a Varig spokeswoman.

The Brazilian carrier also offers one free stopover in each direction with its 30-day APEX fare. Additional stopovers cost $50 each, and might also involve a surcharge on mileage, depending on the routing. Travelers also have the option to fly on other airlines with this fare.