If it's just about the oil, partition wouldn't be so bad. The kurds have oil and are pro US. The Shiite south might be dicey, but couldn't the US just secure the oilfields? The Sunnis will be shut out, and will need dole outs, but that's cheaper than war.
No surge can remove some of the fundamental sticking points of iraq, the militants can just choose to go underground and wait out the US if they decide to. But the resources, the money funding the conflict comes from the outside. Mind you, al Sadr seems to be going for a Hezbollah style army/police/shadow government organization. It's quite a successfull model. That's why he wants the US out - so he can take over.
But how many troops will it need to seal the borders and take out the militias?