Find out where the carrier's gateways are, and use the flight paths to your advantage. You not only can break up a trip, but also pick up another city for free or a small additional fee. In many cases, it's cheaper to reach a destination city by stopping at a midpoint along the route rather than by flying directly to the final destination. Check with a travel agent.
Each airline permits different stops, with varying rules, at a range of costs. There are exceptions, but generally speaking, four hours is the maximum layover for domestic flights, and 12 or 24 hours for international travel.
Airlines also have different policies. If you're heading to West Coast cities such as Los Angeles or San Francisco, National Airlines will give you a free stopover in Las Vegas. America West will throw in a stopover in Phoenix or Las Vegas for an additional $60. That means you can fly to San Diego, stop over in Phoenix for $60 and, on the return trip, stop in Las Vegas for another $60. America West flies to more than 20 West Coast cities.
On trips to Hawaii, most major airlines, including United and American, usually will permit stopovers in some Western cities, including Los Angeles and Las Vegas, for $60 per stop. You have a chance for two stops on outbound flights and one inbound.
Delta offers stopovers in Las Vegas, Salt Lake City and Dallas/Fort Worth. If you have friends heading to Hawaii from the Midwest or East Coast (or practically anywhere the airline flies), they can stop over and see you in Dallas/Fort Worth for $60 on Delta and American. This could be an easy way for parents to drop off children with grandparents while going on a romantic getaway.
International flights frequently allow a connection time of 24 hours. Turn an overseas vacation into a multiple-stop journey by making arrangements for optional excursions. If staying multiple nights, you often can find cheap accommodations as part of a package.
British Airways offers free stopovers in London on most fares to the United Kingdom. This includes destinations such as Glasgow, Manchester and Birmingham. Icelandair features stopovers in Reykjavik at no additional charge on the way to or from other European countries. You can stay as long as three nights. AeroMexico will permit a free stopover in selected Mexican cities on some fares.