I've used Price Line many times. I can usually narrow down which hotel I'll get to 1 or 2 based on features, rating and using hotel lists from betterbidding or biddingfortravel. As others have said if you need two beds it can be a risk as they only guarantee one bed.
Lately I've been using HotWire. You see the price, features and rating but not which hotel. I've found it fairly easy to figure out which hotel it is and gotten some great deals. Hotwire allows you to say 4 people, so 2 beds.
Generally I don't care exactly which hotel I get. I just want a 3 or 4 star hotel, good ratings and in the area I'm wanting.