8. Location Location Location
The Louisiana bayous served as a dark and mysterious backdrop for Season 1, a perfect setting for the show's inherent weirdness that served as the third lead character of the series. It initially seemed like a smart move to switch the action to California for the sophomore outing. It's about as different as you can get, meaning there was scope for a whole different story in a very different setting. In practice, the idea did not work.
The setting of Vinci, somewhere between Los Angeles and San Francisco, proved to be extremely dull and generic. Where Louisiana had the crazy heat and the mesmerising colours, this was an endless maze of grey roads. There have been countless detective tales set in LA, and this one felt more like a by-the-numbers pastiche of them, rather than using the setting to do something different.
Season 3 doesn't need to go back to the bayous, but what it does need to do is go somewhere fresh and exciting; a place that is largely unexplored, and offers ways it can tie into the story while also being extremely visual at the same time.