I play EDH more than anything now, but asside from the command zone everything is pretty much the same no matter what format I play.
Lands are where they are because I tap those more than anything else, also when I declare attackers I tap my creature then advance it towards my opponent so it is easy to know what is attacking and what is not. If my lands were "above" my creatures I could not easily slide them up. Artifacts and enchantments are often global objects (or equip that needs to be equipped) so having them off to the side seems the best. If I have room I try to fan out my graveyard so I know that is in there.
EDIT: I should add that I firmely believe that card position should be standardized for DCI sanctioned events. Even if the standard is different from the way I like it, I just feel like it eliminates misunderstandings and lame "mind game" type attitudes- "If my opponent wasn't paying attention to how I tapped my creature and is confused it is his problem for not paying attention". (just using this as an example) If DCI sanctioned a "right" way it would be easier to know the game state for both players, and a judge that happens by.