Going through each option...I would elect for 2, by the way

1. I think that setting a timetable would be problematic for us and cause greater destabilization in the region. When you set out your timetable for withdrawal, you give your opponent a timetable to cause you problems on that withdrawal. They can focus their efforts on causing maximum damage to us as we're pulling out, which is desirable for the more extreme groups.

2. I think it might make us look bad in the short-term considering the amount of hostility we've had with Iran and Syria over the last few years, but frankly I think that Bush's whole Axis of Evil rhetoric hasn't been particularly helpful to us to begin with and has been a big part of our problem with getting the international community to buy into the GWOT and Iraq. Most of the world probably realizes that Iran and Syria aren't ideal partners politically, but I think most nations start getting twitchy when the biggest superpower starts breaking things down into "good" and "evil" and acting unilaterally. Syria and Iran are not a direct or huge threat to us militarily or economically (since we don't import Iranian oil and since Iran will realistically not develop a nuclear arsenal capable of wiping us out) so it's not necessarily a bad thing to engage them. It's their neighborhood and they would likely have a better idea of how to stabilize and proceed there. The Iranian/Syrian alliance is also in part a reaction to our presence there...if we're out of the mix it could also weaken their cooperation by removing what they perceive as a common threat. We'll also still have troops in the area with our forces in Afghanistan to deal with the Iranians if they get out of hand. And if we've made a legitimate effort to engage Iran diplomatically, it would give the international community more of an incentive to back us if military action against Iran becomes necessary because they won't see us as just trying to impose our will. Engagement may be painful in the short-term but it gives us options in the long run.

3. I think legal trisection would open the gates for widespread ethnic cleansing in all of the territories (Shi'a, Sunni, Kurd). It already happens, and it's currently a major issue, but trying to partition the major cities in particular has the potential to create a massive humanitarian crisis that we would be blamed for (as the British often are for their partitions in colonial times). If trisection is going to be tried, it needs to be Middle Eastern countries trying it, not us.

4. Al-Maliki is a horrible prime minister. But al-Sadr would be far, far, worse, and he's the best bet for being able to control the country (because he controls the biggest armed force and has the biggest constituency). Worst of both worlds if we install him...he'll be hostile to the U.S. and we'll likely be blamed for everything he does if we allow him to take power. Any other Shi'a we install will likely be subordinated by al-Sadr. Any Sunni we install will likely cause the government to collapse (at best) and lead to immediate civil war (at worst). The Kurds don't have enough power outside of the north to fix the situation, assuming they'd be interested in doing so. They might just let the Sunni and Shi'a fight it out. Plus Turkey would likely object to a Kurdish strongman, which means there's a good chance we'd have to go back in if Turkey were attacked by Kurdish insurgents and had to go in (being a NATO ally). There's no strongman out there who could control Iraq that we could live with...better to let the regional powers sort it out, even if that includes Iran and Syria.