Germany in September

Hello. Back to pick your brains. We are thinking of going to Germany in September,maybe do the romantic road and the alpine road and the rhine. But we are a bit confused about the LEZ stickers do we need to get one and where would be the best place ? Also any tips and advice on routes or interesting things to see we would be most grateful. We like the idea of using the Aires sites as we really liked using them in our french adventure. Thanks and oh by the way we have 2 weeks so we may be a bit ambitious.