I could list you up all the satellites which you should theoretically get but i'm sure that some members here have practical experience how the situation looks like in Ho Chi Minh City. Til then you could start taking a look on the coverage zones (Beams) of each satellite between 26E-177W. These positions are above your horizon if no obstacle blocks them. Especially the most western and eastern positions are critical. I suppose the most western position you could get is 49E, the most eastern 177W.
Here are the sites worth for a start:
http://www.satbeams.com/ (register to have full access)
I have also some links of Thai boards but am not aware if you can understand their language and writing. Further on maybe there are some minor or bigger differences in between the reception of southern Thailand and Vietnam. Anyway i will post them too. Probably they will help somebody else also:
Best regards from Germany.