M.C.
I use Hotwire, instead of Priceline; the two are similar in that they give you big discounts, but you don't know in advance the exact hotel you will be staying in (you get stars and neighborhood, but no name). I've had great results, and gotten some great deals on both hotels and cars. I don't use them for airfare because you can't see the times before you fly, and I don't want to end up with a non-refundable flight that's at 5am or midnight or has a 6 hour layover or whatever--too many variables. The downside is that you pay in advance, and it's non-refunable, so if you cancel, you're still out the money. I wouldn't worry about getting totally jipped, though--both are reputable companies, and worst case you can always refuse payment through your credit card if you don't get what you paid for.