I have actually written a few articles about this, specifically one for the Boston Herald where I point out sites "other than" Expedia and Travelocity.
For last minute fares I find Hotwire
to be the best, but the drawback is that they are what the indutry calls "opague" fares meaning you don't see your itinerary until you agree to the price (similar to Priceline, but you don'y 'bid' for a fare, you see the actual price before you commit to buy). Once they show you the fare you have 1 hour to accept it.
I just traveled Phx to NYC with Hotwire tickets and I not only got a great fare but the itinerary was better than any other site offered me. Similarly to Orbitz, they offer seats from most of the big airlines.
Personally, I have yet to find a good fare on Orbitz. Significantly, Hotwire actually advertises on Orbitz as a 'lower price option."
I always check www.onetravel.com
. I just purchased two RT Phoenix to Ft. Lauderdale tickets there for prices I couldn't get anywhere else. Non-stop on America West for prices far below the rate advertised by the airline or any other website. This is a little known travel site, but they have significant financial backing from Lycos and the Travel Conglomerate Amadeus.
I always monitor whatever Travelocity
is selling by customizing my "My Yahoo" start page to watch for good fares to specific cities. It is interesting to watch the fares vary day by day, and sometimes when I see a good fare I jump in and grab it since I fly to NYC pretty often.
I mist say I rarely see a good rate for Air on Expedia
, though I always check. But a lot of this has to do with where you live because the sites get good deals with different carriers who may be more or less accessible to your community.