[Cronos]

The best approach would be

1. to tear off western Iraq and Eastern Syria (the Sunni dominated areas), attach them to the Hashemite dynasty ruled Jordan
2. Give Assad the city dominated West Syria and Latakia with the condition that Sunnis are pushed to the east or they convert
3. Shia dominated south Iraq
4. Kurdistan
5. Yazidi land
6. Assyria

[SunkenCiv]

If it comes to rebuilding the boundaries, I'd go for most of those, but the only thing the Assad family would get is bullets in the cranium. The Hezbollah would be annihilated, and the Alawite and western Sunni remnants of Syria joined to Lebanon.