Ooohhh doing anything by bus in Auckland is a mission. If they want to go to a mall, just go to the Manukau westfield, its pretty big, not as big as Sylvia Park, but still pretty big.

Rainbows End is definitely an all day thing, well depending on how old the child is but hours are 10-6pm or were last time I went (which was years ago)

Going by bus to the zoo or kelly tarltons would be so annoying from Manukau and expensive. Its at least $6 from Manukau to City now. Unfortunatley there are no trains going through Manukau either that I'm aware of, this would be easier and cut down on time. I would go to either the zoo or kelly tarltons if they want to go somewhere on the second day. In the city there isn't really much for kids to do. ( I basically live in the city because of work) Sky tower, and wander round the gift shop. There is the Atrium shopping centre to have a wander round and queen street, go for a walk around the viaduct, which would be even more interesting if there was a cruise ship in that day. I think there is a free bus to kelly tarltons, but the buses go along there quite frequently from britomart, and if your going to do that you can jump on and go a little further through to mission bay for lunch.