S4N, I wouldnt give it up so quickly. What you need to do is to make sure it is right the first time. Make sure its bulletproof. If so, then tariffs and ticketing will be a breeze. At that point, go, dont make changes unless you have to, dont lose your ticket, and drink a margarita for all of us.
But you are off to a good start, and even though its a long itinerary, it isnt terribly complicated.

This itinerary would work fine if the o's are stops and the x's are transfers. The only thing you are doing is dropping Dubai (which I have heard is very expensive and over rated) and changing the order of things.

JFK-oMAD-xLON-oCAI-oLON-xHKG-oNRT-xHKG-
oSIN-oHKG-xSYD-oAKL-xSYD-oMEL-oSYD-oLAX-
oMIA-oJFK

You might also consider,

JFK-xLON-oMAD//AMS-xLHR-oCAI-oLHR-
xSYD-oAKL-xSYD-oMEL-oSYD-xHKG-oSIN-xHKG-
oNRT-oHKG-oLAX-oMIA-oJFK.

With this route, you would be mostly on CX and BA, and all on the big busses. You will probably have to run in Business Class between Hong Kong and Singapore, and maybe between HKG and Narita. Also you will be in Biz for the NZ and Melbourne flights. Otherwise, you are in true first class. The only thing I could see you possibly getting nailed on is the newish rule about the transits in London and Hong Kong. I dont know the exact rule, so someone else can say if its a problem.

The only other thing I would suggest would be to change Singapore to Bali (DPS). I havent been to Singapore, but the consensus seems to be that unless you are using it as a jump point for Malaysia, it isnt all that interesting. I have been to Bali and absolutely loved it.