I'd prefer BKK over SIN for a stopover at any time as BKK is more interesting IMO.
I wonder if there's any chance to credit GF miles to BMI in the near future? BMI has its code on all GF flights ex LON, but unlike the cooperation with QR it's not possible to credit GF miles to BMI.
Apart from this issue, it will be interesting to see if we get BMI miles for the DUB-LHR op by BMI but with GF flight number.