I can see where those who thought that supporting the revolution in Libya might think that the same would be true in Syria, and I can see where the fall of the Syrian regime might be even more in the world's best interest than the one in Libya.
Libya was relatively straight forward though - bad guys vs. potentially somewhat less bad guys. Syria has the same, but in a different neighborhood and throw in Hamas, Hezballah and any number of other Palestinian extremist groups (who would be more than happy to take a shot at anyone who set foot in the country) and are overtly supported by Syria and Iran. I could see Lebanon, and possibly Jordan drawn in (probably not nationally, but in a revolutionary sense) and if (when) things begin to implode, who is to say that Assad and his military don't "go Saddam" and launch everything they have against Israel right next door (they've got a pile of surface-to-surface missiles). If that were to happen, all bets are off.
Too many moving pieces to guess where they might fall together. What do I know though, I'm just an old mechanic...