Getaroom.com
I'm helping some friends book a California vacation and I'm finding this agency's rates (which are non-opaque) to be the best out there: often cheaper than the chains themselves (might want to try some best price guarantee claims) and easy to deal with online. They claim to sometimes have lower rates if you call their 800-number, but the three times I've called, the rates were actually cheaper on their website!
I'm basically using this as a back-up to priceline. I'll bid up to $20 less on priceline (including tax and fees) from the all in rate of a decent getaroom hotel (4 star tripadvisor reviews). At that point, I figure the risk of priceline isn't worth it, especially if I can score a decent hotel with free breakfast on getaroom. In both LA and Orange County. my $20/under bids on priceline were rejected. Getaroom rates do pop up on Kayak.