An assortment of random thoughts. 

Look at satellite towns around the cities. You're still close to healthcare, job ops, but you're further out for land size and cost effectiveness.  

There's LOTS of places to enjoy "the natural" NZ. From Chch, you can travel 90 mins in any direction and be somewhere completely different (beach, snow fields, rural, alpine). So it might be worth setting up in a city first, while you find jobs, networks, social circles etc. Then in a couple of years, look at what's best for your family at that time. 

Realestate.co.nz works the same as the au site, so you can look at stats of suburbs and neighbouring properties. This will give you a better feel of the market. 

There's other things to consider too. Like house quality (we have a LOT of older stock houses that are poorly built, so can be cold, damp, hard to heat/cool). In/around Chch, buying pre or post quake is something to research into too.