I haven’t, but you have to consider all the risks of using Priceline. You might get an inconvenient itinerary (but within the parameters Priceline sets, so it can’t be too terrible). Your tickets are most likely absolutely unchangeable for any fee. You won’t get frequent flyer miles. And most importantly, good deals are few and far between.
 
But if you keep all that in mind, you might as well give it a try, after doing a thorough search to find the very cheapest possible flight through conventional means.
 
I do love Priceline for hotels, particularly in London and Seattle.

BEWARE OF PRICELINE!!! It is very easy to get stiffed and it has happened to thousands, me included. It is not for the unsophisticated traveler, and if something goes wrong along the way or your itinerary is flawed from the get go…you are screwed. There is not a chance in hell of getting help from priceline, or even getting a hold of anyone who will listen. Do a search on the web for unhappy stories and you will find many, many, many. I wish I had done a little research before hand. My story is too long to relay, and I am trying to forget. Again, just beware, and if you’re not a truly seasoned traveler and going abroad…get a reputable travel agent to set up your itinerary. But don’t just take my word for it, do a search.  

I agree w/these comments.

I use priceline OFTEN for hotels – it’s a great site for that. As far as Airfare and Rental Cars, don’t waste your time. Too many risks and not a big price benefit – you can do better.

If you are looking to bid on hotels, sites like:
www.biddingfortravel…
www.betterbidding.co…

Are invaluable as you can get bidding strategies and get the best deal.

Enjoy

-A