Assume you realise that if you arrange your own flights you miss out on the transfers, the complimentary 1n hotel and the guarentee of getting you to the ship if your plane is late? As for where to stop - well - Singapore is clean and clinical like an Asian Switzerland; Hong Kong is buzzing and vibrant; Bangkok is my favourite but be prepared for chaos and poverty, and KL is also very nice and often overlooked. You could also go via Dubai on Emirates.
Most of what "A of N" says I agree with except that if you intend to stay on or go early “cruise only” can be beneficial. I have also found that RCI and Celebrity prices to NZ and OZ are unrealistically high for next year and there are far better deals to be had. You can only book eleven and a half months ahead and that, of course, can only be from your return trip date so work it out and book as early as you can. I prefer Singapore although Bangkok is also good but if you have 2 days in either place they will make you a very good suit at a good price in that time. Hope you both enjoy your trip, Mr. Jones, .....Nei.