dress code's and traveling in New Zealand

Coming from Colorado and how informal people are there, I am curious
about New Zealand. Are there places in NZ where if you go to eat at,
etc. they are particular on dress code such as no jeans, sandals,
shorts, etc and dress clothes is expected ? I plan on traveling down
there next January. I am wanting to pack very light as well.

Also, do dress codes vary from region to region such as cities
expecting more versus places like Queenstown (by the mountains) where
people are more informal ?