I've used Priceline 3 times for hotels.
Three years ago during Spring Break, I was taking the kids to California and we planned to visit Disneyland. I ended up getting the Hyatt Newporter in Newport Beach for about 25-29.00/night. I can't remember the exact rate I got but when you're paying in the 20's does it really matter. We stayed there for a week and it was fabulous. It was about a 20 minute drive to Disneyland but we planned to have a car anyway since we were doing alot of sightseeing.
For Disneyworld, we were going to arrive very late last summer and I didn't want to pay the BC rate for our first night since we wouldn't get there until 1:30AM. I used Priceline and got a hotel at the airport. Can't remember which hotel but it was a major resort type and the price was 45.00.
Also last year, I went to Minneapolis and got a 4-5 star hotel for 50.00/night. I love using priceline.com for hotels.