I want to book a trip ORD-BKK in 2008, either spring or fall. Is there a best time to go to get a good rate on the flight? Do flights to Asia ever go on "sale"? And, are there any Asia-specific travel sites that would have better deals than trying to use SideStep/Expedia/Orbitz?

I am kicking myself for already booking a flight to Hawaii in October, now that I see that UAL has reduced them to <$450 r/t from ORD, while I paid $700+...

Any help would be greatly appreciated! Thanks!