Nick!
heres the deal
www.hotwire.com USE IT! You will not be disappointed. SF hotel occupancy rates is really low so you should be able to get a really good deal!
Check out
www.biddingfortravel.com as well on how to use Priceline and a listing of hotels in SF Hotwire uses.
I have used Hotwire and its good, They segment the city in districts so you pick where you want to stay along with how many stars each hote is rated. They are pretty damn honest about there ratings too.