If you're looking for a place to enjoy breakfast or lunch while your kids play on a large open lawn and go on horse-and-cart rides right in front of you, think of visiting the Joostenberg Deli and Bistro on the Klein Joostenberg farm.
The farm is on the R302, the long road that leads from the N1 national highway to Stellenbosch, so it's pretty convenient if you're planning a day trip to Stellenbosch. Kerry-Anne and I had an early breakfast under the trees at the bistro. The food was tasty (albeit a little rich for our delicate digestive systems), and the service was great (although, I guess having a friend wait on us has its advantages ;) ).
The leisurely horse-and-cart rides on the lawn cost R10 per person, and I *think* adults can join in the fun. If we weren't in so much of a hurry to get to some business in Stellenbosch, I'm fairly sure that Kerry-Anne would have insisted on a ride. :)