Since the Assad regime will almost certainly be replaced with an even more noxious group, why would we bother?
I'm thinking it's popcorn time.
Syria is ruled by minority Alawite Shiites. Its population is mostly (70+%) Sunni. Look for Muslim Brotherhood and al Queda to support the rebels, and the Iranians to support the government side. Ideally, the fighters on both sides will kill each other off.