We booked a UA awards flight back in Dec to Laos and have a stopover in Bangkok for 3 days. We got some tips through FT that told us to research available awards flight on Star Alliance carriers through the ANA website (you have to register in order to search). It makes it much easier to actually book your flights with the agent when you call if you have the flight numbers, the class of service you want (the website will show you availability in F,C, and Y), and the dates worked out. We were able to get seats in C on UA, ANA, TG, and SQ, and it will be even easier if you have flexible dates/locations.
Good luck!