Located just 45 minutes from Auckland on SH 16 - just north of Kaukapakapa - is the Kaipara Coast Sculpture Gardens , Garden Centre and Cafe.
There is an easy undulating walk mainly in shade past 40 different sculptures - I'm not going to comment on them because my taste isn't everyones.
In the garden centre (really healthy looking plants) there is a small cafe with an understandably limited selection but there are lots of picnic spaces in the shade. I went with a couple of 80+'s one on a walking frame so should be easy for most.
Highly recommended (small entry fee) for a morning or afternoon out.