Naruto sucks at genjustu because it takes precise control and small amounts of chakra. What if he bypassed that issue by simply casting AOE genjutsu so large it basically captured a village? He would have the ability to basically alter the reality of everyone around him. It would be a once a day kind of thing, with a massive amount of chakra molded quickly. He has the imagination. What kind of genjutsu would he cast? Something demanding respect and adoration, which he would quickly grow bored with. What would he do next? He'd try a series of things, pranks, gags, and jokes, but eventually would realize that life was empty when living in an illusion. He'd end the illusion and concentrate on real life, as what he's doing would be too close to the moon-eye plan to make him comfortable.
When would this take place? This would take place while in the academy, I think. It would change his outlook on life dramatically; fantasy might be better than reality, but you can't live in a fantasy. It would be a darker look at psychology.