Delta prices one-ways as round-trips, with a phantom return in the same class of service and low/medium/high band. Thus a low coach ticket one-way from Southeast asia region to US-49 could be 80K Delta miles.

http://www.delta.com/content/www/en_...east-asia.html

Lots of Delta SkyMiles carriers for award travel can't be booked online, or can't be searched easily across flexible dates on delta.com.

I believe that SGN-IAH may be one of the rare Asia-US city pairs allowing routing across the Atlantic by virtue of an Air France fare filing. I would look for SGN-CDG-IAH at a coach classic level on the Flying Blue search engine www.airfrance.us and then call Delta to book. I expect the experience will bring incredible frustration.