If crazy golf is your scene then you're sorted. Otherwise, from my stay there a couple of years ago, the major nightlife is ambling down the aisles of one of the many local walmarts.
Religion seemed to be a big part of many people's lives down there too - probably since it's the only way people will develop a sense of community in such a sprawly faceless part of the world.
There's a pleasant (albeit small) park area in oldtown Kissimmee though.