Advertisement Watching Some Kind Of Heaven, an entrancing new documentary about life in a massive Florida retirement community, the mind may drift to a whole library of movies about the plastic unreality of suburban life. Partially, that’s because the film’s director, 24-year-old Lance Oppenheim, plainly takes some cues, visual and tonal, from touchstones of the genre. But it’s also because his subject, the so-called “Disney World for retirees,” was essentially built from the same psychic blueprint as those films: the nostalgic dream image of an unblemished American yesterday, a boomer paradise more imagined than remembered. What Oppenheim has found, in his first feature film, is a real place every bit as art-directed as