Waiheke Island, located in the Hauraki Gulf just outside of Auckland. Just a 35-min ferry from the central city to this little piece of paradise. A deceptively small island, there is always something to do. Over 27 Vineyards, many beaches and of course great people. And it's a great place to Couchsurf :)
Note you can take your own bicycle over on the ferry for free; you can also get around on the island by bus, or rent a scooter or car. Hitching is common & considered safe on Waiheke also.