Here are some shots from the film adaptation of Cormac McCarthy's The Road. It's Stars Viggo Mortensen, Charlize Theron, and Kodi Smit-McPhee as the boy. It will be released this November.
I think Viggo is a good choice for the the father and the images look appropriately grim enough. The Road is about love, and it's about survival, but don't call it post-apocalyptic sci-fi because the masses would never enjoy anything like that.