There's a few to choose from, depends where you want to be, there's a couple along the Torrens river and a couple down West beach way in addition to the Brownhill Creek one. There's also one up at Mt Barker which is within 30-40 Mins from the city.
We are currently staying at Woodcroft Park at Woodcroft that is part of McLaren Vale. Small park in terms of powered sites, has large sections of permanents but well maintained, clean and close to beaches and shops as well as McLaren Vale Wineries.