I have become very fond of tripadvisor.com When I put in my specific hotel, it will check most online sources at once for quotes for my dates (hotels.com, travelocity, expedia, travelweb, etc.)

It seems that EVERY TIME, hotels.com show "no availability" At least 2 or 3 of the other places show rooms. I can't figure it out but I'm pretty sure I don't want to use them of they have such limited resources.