If you use iphone for satnav and audio, the armrest position is a pain due to required lead length (obtaining thereof) and necessary routing (avoiding handbrake, gear lever etc etc all the way up to the screen) - all ends up very ugly. I've ended up retiring an old iPod Touch to the armrest for music, and iPhone on the window for satnav relying on it's internal speaker, but this means I have to manually keep the iPod up to date rather than letting iTunes Match do it's thang.
Between the 12v sockets is much more usable in this regard...