They would never play in in NZ.
Why not?
Sure broadcasters might bitch and moan that it couldn't kick off at 8pm AEST, but I doubt that ratings would take that much of a hit if you kicked off around 6pm AEST, and it'd be huge if you went about it the right way.
If the yanks can manage the time difference between the East and West coast then I'm sure we can find a solution that's workable here.
It'd be a bad idea to do it regularly, but every now and then it'd be a good change, and huge for the sport and NRL's profile in NZ.
They would never play in in NZ. So you are left with just Brisbane and Sydney. If each city can only hold it every second year, the other city could bid $1 as there are no other suitable rectangular stadiums.
Bidding is not the way to go. Tie cities in with multi game contacts and then you can demand whatever you want.
EDIT - Homebush is not rectangular. Marvel with the seats in hold 56K. More than enough. The AFL could host the NRL.
Firstly, we both knew exactly what I meant when I said rectangular, but you have a fair point about the lack of competition for the event.
Maybe you could change the criteria to something like cities will only be considered so long as any new large stadia that they build is rectangular, or can be configured to be rectangular. That way Optus and Adelaide Oval would be eligible to host it initially, but when it comes time for Perth and Adelaide to upgrade in the future they have to include a rectangular option or they won't be considered anymore. Or at least something along those lines.
I totally forgot that Marvel can be converted into a rectangle, so that's a third/fourth stadium that could host it straight away. BTW, as long as the cheque clears who gives a shit if the AFL owns it.