Great advice above on all counts.... but please remember that driving a decent 4x4 capable vehicle in Argentina will be quite a bit more expensive than anything you would pay for in North America, especially if you cannot drive a stick. The economics of such a rental will mean that hiring a vehicle+driver combo very quickly comes into play. Also, if you are into wines and plan to visit wineries, remember that the driver option allows you to enjoy more juice and not worry about safety/legal issues of a DUI related event......