Cornwall Park is huge. Head for the Cornwall Park Cafe, which has great natural loops around the garden (which kids love) and coffee & tea (which parents love).
The most direct way to get to the tracks is via Pohutakawa Drive, off Greenlane West; however any of the roads into the park will get you there, and if you’re not familiar with the park, the map is helpful.
There’s lots of parking: the cafe carpark is the closest, but it can be busy so you might need to park on the side of one of the roads. Once you’ve driven into the park, just follow the signs to the cafe (not the bistro). There’s a public toilet next to the carpark by the cafe, and a nice little ice cream shop.
The tracks start on either side of the cafe, and there are some lovely loops to follow. The rotunda offers a nice spot of shade for playing in, and if it’s quiet enough, the little ones might enjoy speeding down the ramp there, or bumping up and down the very shallow steps.
Other highlights include biking through the tunnel of wisteria, and the paths through the paddocks with the sheep (watch out for the fresh droppings!).
There is a playground there. It’s very retro.