Which route? I would not upgrade on short-haul... Not worth the money/miles/certificate...
I am planning to do SIN-IST-BUD(or PRG)//VIE-IST-KUL.
I can only do oneway upgrade as I do not have enough miles to cover both way.
So I have to choose outbound or inbound. Prefer outbound as SIN-IST is longer flight than IST-KUL and also hopefully I will get better rest to start my vacation.
The mileage requirement is the same for SIN-IST or SIN-IST-BUD/PRG/VIE.
BUD seems is being served by 738, while PRG is mixed 321/320