1. Trip planning sites have several services that slice and dice your flight inquiries in any number of ways. They can search one-way trips, round trips, each leg of the trip, by price, by date, by time, and by multiple airports.

2. They typically offer services to alert you to when low fares for desired routes become available or to examine baseline fares offered by airlines throughout the year.

3. Many sites, such as Travelocity.com has airplane seat maps for 13 airlines, in case you want to choose your seat too.

4. Many trip planning sites also have hotel room finders and car rental options. CheapTickets.com has a Fare Aware option that shows what other passengers paid for a certain trip at the same time last year. For the top 1,000 routes in the United States, the service shows the average price, average number of passengers, what a one-way trip costs, the airline that flies that route the most often, and the low-fare courier rate. While some sites do international flights too, others such as Yahoo! only search within the Continental US, Canada, Puerto Rico, and the U.S. Virgin Islands.

5. You can often find sweet deals at the last minute. If you want to fly on a whim for the weekend, this is really the best route to go.

6. At www.SmarterTravel.com, you can do all of the above but also sign up for a weekly email with cheap fares available for the coming weekend from airports you can access. Its flight search option shows all flights leaving the day you are interested in but when you click on the price, you are bounced over to www.expedia.com. It also advertises the latest travel bargains and ongoing airline sales.

7. Popular sites include:

SoYouWanna know more? Check out our full-length article SYW plan a trip to England?