Tried hostelworld.com for US and Europe. Good for low-end accomodation and dorms.

Tried agoda.com for Asia. No complaints. Just that the reward points are only valid for one year. I did not know that and missed the opportunity to use them. With China, you can make booking without paying deposit. Done that through a China hotel site, can't remember the name.

I doubt you can get 'cheapest rates' on any single site.

This post has been edited by tehtmc: Sep 9 2010, 01:27 PM