The sweet spot for buying plane tickets seems to change all the time. Kayak.com
now says its customers are finding the lowest domestic fares 21 days before travel, and the lowest international fares 34 days before. Whenever you buy, though, you should use the site's Add Nearby Airports tool; it's a box you check off right under the From and To city fields—but a Kayak rep told us only one in five users actually does this. We recently searched the site for a round-trip ticket from JFK to Fort Lauderdale (it's one of the most traveled routes in the United States
) and came up with a $241 fare. Clicking on Add Nearby Airports shaved off $41 and brought us to nearby West Palm Beach. Depending on your final destination (e.g., if you're headed to Boca Raton, which is about halfway between the two Florida airports), it may not matter which one you fly into.