I also use betterbidding and biddingfortravel to help with bidding strategies for hotels and car rentals. By reading through the forums you can see which star ratings/hotel names are in the area you want, and other people post their bids. You can also learn bidding strategies so that you can get free rebids without waiting the 24 hours to rebid.
I've been using priceline since 2005 when I booked a San Diego hotel for a vacation and haven't turned back since. I did get burned for the first time this past October though. We went to
Disneyland and I wanted to book our last night for a 4 star hotel right on the beach. I knew we'd get one of two hotels since those were the only 4 stars via priceline in the area.
When my first bid was rejected, I used a free rebid on a hotel for the Anaheim area. I bid on a 4 star, but there weren't any 4 stars in the area, so I was hoping it would snag me the 4 star by the beach (since that was the only other area in my search criteria). Well, one of the hotels in Anaheim that priceline had rated as a 3.5 star had just been upgraded to a 4 star, but it wasn't listed on the betterbidding or biddingfortravel websites as being a 4 star. So we ended up at the Anaheim Hilton for our last night, even though we wanted to be by the beach.
If rental cars are expensive during your visit, they'll be higher on priceline, too. I've been lucky and have also rented for $10 per day for a full-sized car from MCO, but other times I've ended up finding better deals on websites like
http://www.rentalcars.com/search/?putype=air&dotype=&citypu=Phoenix+-+Sky+Harbor+Intl%2C+US+%28PHX%29&citydo=&pudt=10%2F22%2F2011&putm=09%3A00&dodt=10%2F24%2F2011&dotm=09%3A00&companydc=
Just make sure you book a rental first that you can cancel. Keep that as a back-up in case you can't get a lower price on priceline. I start low and then bid up a dollar a day until my bid is accepted. That way I know I've received the rock-bottom price.