A warm welcome to the forum Dave, you will really enjoy being part of our little family, well big family really..!! Loads of info and chats on here...enjoy..!!
Re your original question, if not rushing and loads of traffic, just leave it in auto, if you can get on a bit switch the sport on. Open road stuff switch auto off and when the weather is OK select sport. DO WATCH IT IN THE WET..!! These cars have a lot of power and sport selects a less controlled antiskid etc., than normal so that you can enjoy it in the dry, in the wet it can very quickly get away from you if you are not careful.