We used priceline in 2004. We were quite happy with what we got in Tampa & Orlando. As SeattleRedBear said, they have a strict cancellation policy & you have to be comfortable with not knowing where you will be staying until your bid is accepted. Another site for bidding help is biddingfortravel.com, but beware that the owner of the site is VERY fussy about how you ask for help...have heard her called a nazi, lol. If you follow her rules, you will get good advice. Helps you with how much to start your bid, how to get free rebids, etc.
For Orlando, we only wanted resort level. We got the Marriott Orlando World Center for $83/night. EXCELLENT price for the level of quality. Beautiful resort.