Have you been to All Children's Park in Port Orange? I just went myself this past weekend, for a birthday party.
The park is nice and the kids loved the playground area. There is also a boardwalk to take a short nature walk on. In the summer, you really need to plan your visit early in the day, or later in the evening, to avoid the heat of the day. The playground area is not shaded, so if you go in the middle of the day in the summer it will be really hot!
All Children's Park is located at 5959 S. Spruce Creek Road in Port Orange. There is a covered pavilion, picnic tables, a dog park, restrooms, tennis courts, and softballl fields. Here are some pictures of the park: