I'd say it is logistically near impossible to do both in the same day, unless they are having late summer hours. And as skylady says, it's too much for children and adults. Further, both are quite expensive. I'd want to maximize my experience and have time for the great animal shows, particularly at Wild Animal Park. I love Wild Animal Park, and recommend it if you must chose just one. However, should you be visiting in mid to late summer, be aware that Wild Animal Park is further inland and can be scorching hot from midday onward.