Chimbu, me too. Never mattered to me whether it's was a DC3, C310 or hang glider (and yes I have flown all sometimes on the same day) the flare height is simple. Whatever the half wing span - which you can usually see by simply focussing on the wingtip for a few seconds somewhere down final approach - is the height to think about flaring. There is nothing magic about the flare - simply reduce the rate of descent to something that the gear and passengers can stand while simultaneously removing power/thrust. Most aeroplanes are pretty good at landing themselves if not over-controlled. Watch an auto-land sometime - the automatics seem to do very little other than level off and chop the power.
And all this bullsh!t about looking at the far end of the runway? Instead try applying the first principle of motor-cycling i.e. 'you go where you look'. So if you look at where you intend to touch down, that's where you will touch down. Unless you are going too fast or do something silly in the flare like pull the stick back into your guts.