There are a couple of things to be aware of.

1.) A UA/MP-issued Star Alliance business class award, that incudes segments on SQ on a 2-class aircraft, means that you have to sit in economy. This is a new rule, referenced in several other threads, both here in the UA forum and in the SQ forum.

2.) According to the UA/MP Star Alliance award chart, "No stopovers are permitted on awards wholly within a geographic region.", so since Vietnam and Indonesia are both in South Asia, you could not have a stopover in SIN or BKK. At least that's how I understand it.