I have only used Travelosity and Orbitz. They are about the same. I only go through the airline now I have frequent flier points...don't see a lot of difference.
Open the Chase credit card and spend $2,000.00 on it. Once you do, you receive 50k Southwest Rapid Rewards points. It says "Two Round Trip Tickets" but in reality, it's 50k points, so you can squeeze as many flights, roundtrip or otherwise, out of it as you can get from 50k points. Comes out to about $800-$900 in airfare for free.
Now it sounds like that's a lot to spend ($2000 to get $800 in airfare) but if you have something or somethings that you were gonna buy anyway that can add up to $2000, put it on the card and you basically get free airfare.
I did it with a vacation I am planning. I put the reservation on the card, then got the airfare points for the flights. So it basically saved me hundreds of dollars in airfare that I otherwise would have had to spend.
There is a $69 annual fee too. So it actually comes to $69 for $800 of airfare (again, once you've spent $2000 on the card).
One trick I have heard is that the airline ticket sites will put a cookie on your computer and if you come back a second time they will display higher prices. This is becuase their studies have shown that repeat visitors are more likely to purchase tickets. So if you are going to make a purchase either delete your cookies first or use incognito mode in your browser.