Book enought flights to circumnavigate the world, then book a return trip flying in the other direction, all 1st class! That'd possibly earn enough miles to buy an aircraft!!
OK - on a more realistic front .... I have no idea and would be interested to hear some sensible replies as I am a points junkie and have half looked at the NBD 'infinity' card that offers points for spending ......... not got very far tho as I get bored with reading the small print!
LLx