1. FareCompareFareCompare updates its fares constantly. You can also search for the best First Class airfares as well. How is it different from other sites? "FareCompare gets the raw fare data from the airlines directly and we process it several hours before it is available on the online travel agencies and many times the airline sites themselves."
What I like about the site is when it finds a deal, it is still there when you try to book it - sometimes even at a lower price. I recently found a special with FareCompare for $471 roundtrip New York - Moscow all taxes and fees in and when I went to see how it would price for booking it, it was even LOWER - $435!
2. FlyCheapoFly Cheapo details current airfare deals in Europe. Great place to find good prices for travel within Europe.
The choices can get overwhelming, and the site does send you to the low cost airline's site to book. What I like about the site is that it can help you find who flies where fast, and gives you a list (and links to the budget / low cost airlines that fly the route).
What I like about the site is the variety of family offers, often with hotel / air included.
4. KayakKayak maintains a fairly comprehensive list of current airfare and vacation deals. It has a simple, user-friendly interface and scours dozens of sites for the best airfares.
What I like about the site is that it is easy to use, and the vacation deals they find are often really good - like nearly 2 weeks in Thailand from the US including hotel / tours / flights and many meals starting at $1200 per person.
5. OrbitzOrbitz often has the lowest airfares you could find. They also are pretty good at alerting you to specials right on their front page, and for things like hotels provide a really decent range of hotels at different price points and ratings.
What I like about the site is their price guarantee - it's really solid. "Get a Price Assurance refund if another Orbitz customer books the same flight for less." I also think this policy is truly customer-friendly - "Cancel a ticket online without airline penalties by 10 p.m. CT the next day."
6. TravelocityA huge online booking site. Lots of Hot Deals on flights listed, and updated daily. The site has the feel of an expansive travel agency - so many options to think of, deals to look at, and places to consider.
What I like about the site is the sheer variety of flight, vacation, and deal options. It can spur the travel imagination!
7. TravelzooDeals are to be had here. Lots of great last minute airfares. Solid choice of vacation packages and other specials too.
What I like about the site are things like their top deals of the day and top 20 airfares which seem like they were chosen after comparing what is out there. Feels like a lot of the leg work is done for you.
8. VayamaI have mixed feelings about Vayama - on the one hand they often track down amazing airfare deals and on the other those same deals are often gone when you try to book them. So if you hit - great deal. If you miss - a bit frustrating.
What I like about the site is its focus on international travel, and several times when I've checked they are able to quote fares that are lower than many of the other big sites out there.