Wellington is a small but cosmopolitan city and has a football team so don't discount it because its the capital. The city itself is under 200,000 with an urban area of under 500,000 so tiny by international standards.
I don't know much about Napier / Hastings but New Plymouth is a nice city. Both areas will provide a great lifestyle depending on what your interested in, jobs may be limited. I'm moving to the Queenstown lakes district and am finding that there isn't many job opportunities for my girlfriend so you might be in the same boat.
Like most rural areas around the world both have a bit of a reputation of red kneckness, although probably undeserved you should look into the suburbs that you want to move to. I know my sister had issues living near the Stadium in New Plymouth after rugby games and the like. Saying that New Zealand towns are quite urban / not backwards, you will find plenty of culture.