You can google images of '12 G37s with aftermarket wheels. However, you should give thought to the whether or not you want to purchase aftermarket 20" wheels that have the exact same specs (offset/width) as the OEM 20" wheels or not. If you get wheels that are different than the OEM specs, you will need to consider issues such as brake/fender/suspension rubbing.
More importantly, what will your budget be? If you're willing to spend at least $4k for the wheels alone you can buy high quality aftermarket wheels. If you're really into the OEM 20" wheels, see if you can locate a quality set of used/take off wheels on the likes of ebay.
A navigation/software update may improve the bluetooth connectivity, if your car's bluetooth software is integrated into the navigation software. But just a heads up that the Nissan's bluetooth connectivity can be fickle on vehicle's leading up to '12 model years.