Hi Frazzle (from a fellow Kiwi!)
I really really suggest you hit the outlet shopping. Oh my G,..... it is just so awesome! You have a few choices but the two main ones are either Citadel Outlets (closer) or Desert Hills Premium Outlets (further away but bigger). Both have tour buses that will pick you up from your hotel and return you to your hotel at the end of the day. I really do suggest you consider these. Google search both outlets and see which one would suit you best.
There will be just so many choices of things to buy for your whole family!
Another suggestion is Target. Have a look at Target. com and you will be able to see some of the things they have. Okay don't suppose it will have nike etc. but they do have brands such as mossimo (sp?) sooo much cheaper than NZ. They also have really cheap makeup. An example is the maybeline (sp?) brand of mascara I use is $20 here and I picked some up for $3.80! Now even with the exchange rate (which I noticed is on the way up

) that's still cheap. I suggest you go and check out what colours, brands etc. of makeup you would like here so when you get there you don't have to spend time trying them, you can just put them in your basket

!
Target is on Harbour B. - you have either taxi it or jump on the ATR and get off at the closest stop. Target will also have awesome toys, stationery, craft stuff etc. etc. for your kids to spend their money on. and they would be able to pick up their supply of USA lollies etc. to take home.
Have fun - we will be there Oct 3-8.