More details as promised:
Day 1 (Adults with Kids):
Discovery Science Center (2-3 hrs)
Jurong Bird Park (2-3 hrs)
Singapore Zoo + Night Safari (3-4 hrs)
Day 2 (Almost everyone):
Shopping
Tangs Shopping Center (almost everything)
Wisma Atria (almost everything)
Lucky Plaza (cheap deals/electronics)
Ion Orchard (almost everything)
Chijmes (food/wine)
CenterPoint (almost everything)
Plaza Singapura (almost everything)
Raffles Square/Riverside (shopping, Dine & Wine, ideal for dinner)
Try Sim Lim Square if you wish to buy any electronics stuff, you can get some good bargains.
Avoid Little India on weekends to maintain sanity
Universal Studios is definitely worth squeezing into places to visit
Day 3 (Adults with/without kids):
Some beach fun
Sentosa & Siloso Beach
Mega Zip Adventure Park
Underwater World & Dolphin Lagoon
Vivocity (it has some good shopping, restaurants & views)
I stayed at Siloso beach restaurant for a week before relocating, it was quite cheap compared to hotels in city, pleasant view, plenty of walks near beach & just about 5 mins journey to Vivocity.
Three must have been some good new places that came up within past couple of years like Universal Studio, Casinos. From what I have heard, these are just amazing places.
**Don't forget to put lots of suntan lotion, otherwise you might find it difficult to convince airport authorities in NZ, that you are indeed the same person on passport