Seating
 

I'll be flying CX for the first time in June, in Y, from MEL to Hong Kong to AMS and return. I'm 6 foot 5, do CX allow pre selection of seats, and what is the chance on an exit row? Also what are the best seats for some one with really long legs! Thanks for your help

You may request for an emergency exit. But there is no guarantee you'd get one as those seats are mostly blocked off.

But a warning to you.. the emergency exit seats though have better legroom, are actually smaller in width due to the controls of the IFE. So if you are er, of a wider girth around the waist and hip, you might find it rather 'snug'.

RB,
If you sign up with the Marco Polo Club, admittedly with a cost of USD50, you can request and most probably be assigned an emergency exit seat. Even when I was at the lowest tier they always gave me an emergency exit seat when I made the request, sometimes several months beore departure.
When you ask for the emergency exit I would suggest aisle since this means you are A)not squeezed between 2 people and B)not sitting right by the door which has the liferaft attached to the bottom, sticking out and cramping your space.