They way I see it:
Going Big would result in the most dead Americans and Iraqis, and the most animosity against the US from the subsequent Iraqi state/states, which also implies the most subsequent terrorist attacks. It's essentially the Vietnam option, and would be equally successful. On the plus side the US economy will do well from the brisk trade in arms and materiel, but the defecit will be enormous -- it is currently set to be the most expensive war since WWII.
Going Long would result in less dead Americans and Iraqis, although the permenant bases that this will lead to may lead to about the same amount of animosity against the US (and thus terrorist attacks) from the subsequent Iraqi state/states. On the plus side many of the terror attacks may well be directed at the US bases rather than the US itself.
This is the course the US will take. It will end with the subsequent Iraqi government imploding, a decent into chaos and then an anti-US government/s arising.
Going Home would result in the least dead Americans and Iraqis and the least animosity & terror attacks. It would end with the subsequent Iraqi government imploding, a decent into chaos and then an anti-US government/s arising. Just like the other option. I'd go with this one -- you're going home anyway, and whatever government you leave will collapse anyway, so why prolong the agony? Although if it were left up to me I would have chosen the optimum option: "Don't go in the first place".
As to the "what if..." WWII scenario: given the circumstances surrounding the start of the Iraq war, perhaps a more analogous question would be "Should Germany/Japan have gone home instead of invading and occupying Europe/Asia?" There the same scenario does at least apply, no "what if?" is required: they did endure insurgency and uprisings when their troops were "rebuilding". So which was the right choice for Germany & Japan? Go Big, Go Long or Go Home?
