if you think about it, its not really in the movies as much. in the 1st movie, tantoinne was the setting because it was one of the few planets left where slavery was still legal. little ani had to be a slave because in the end, qui-gon would have to choose the boy over the mother, which in turn would basiclly kill the mother because she stayed on the planet. Ani's remorse over what happened was one of the more important reasons he went to the darkside, to save those close to him, blah bla blah, you get the rest. in the rest of the films, however, luke is on tattoine because thats where his aunt and uncle, ani's half brother and half sister, where to raise him, and obiwan was there to watch over luke.