For me, I got most of my rooms through http://www.latestays.com/

They have some decent discount on certain hotel sometimes.

Yeah, it is only 28 days in advance. I usually travel during a non peak period so there is no problem getting the room within 28 days. If you are going during a peak period or scared that cannot get any room, you can try http://www.asiawebdirect.com/

Some site offers cheaper hotel rates but more service charge so it might come out to be more expensive. Just google around and compare the rates.