Guys

Our trips would have 4 sectors - all in Suites.

Only the SIN LHR involves a choice between day / night flights.

The return LHR SIN (and others) would be in daytime.

Plus, we had done Suites before.

So, I guess I'd go along with my +1's preference for a night flight which might just make the body clock adjust better by going to bed say 3 hrs after departure.

By that time, your body would be tired (4am SIN time) which makes sleep come easier.

Waking up (after some Melatonin) after 6 hrs of sleep you would face LHR after a "full night".

Theory, of course.

I may be proven wrong, arriving in London with weary eyes and all-day yawning.