Why carry 2 devices when you can get 1? Get yourself something with built-in GPS and save $ and lbs. There's the Galaxy Player 4.2 for $180 or so. Or, for $300, you can get the Google Nexus 4 (it comes unlocked--just don't bother activating the phone service).
Apple stuff is overpriced and, in the case of the iTouch, underfeatured.