1000m of good condition tarmac that is 'unplottable' in a Harry Potter style so that I can practise and practise to my heart's content unseen. No one watching/laughing, no one cutting me up on final or blocking my runway and no one making late downwind calls when I seem, spookily, to be late downwind too and distracting me.
I'd only need it for about a year or two I'd have thought before I can fly a flawless approach and landing every time.
Oh yes, and with a little dial for wind speed and another for direction and a button that turns it into 450 metres of lumpy grass so that I can set my challenge according to my mood.
In fact, why stop there? How about my own 40 square nautical miles patch of Class P (Penguina only) airspace, extending up to the tropopause, so I can practise everything else too? I could charge people for transits to pay for my aeroplane.
I'm good at this fantasy lark, me.