Any sort of action on the US's part will be viewed ultimately as imperialistic, meddling, and self-serving.
There's no plan or chance of actually destroying the chemical weapons or hampering Syria's ability to use them, they won't invade and supplant Assad (and even if they did, who steps in—what sort of culpability will we have in any future potentially malicious actions that occur as a result— and what's our responsibility in "stabilizing") so what will really be accomplished?
There's no clear defined terms of operational success, there's no tangible goal to be accomplished, and no one internationally will view the US's military involvement in a positive light.
This is an absolute no-brainer. The US should in no way, shape, or form attack Syria. To get mired in yet another international conflict that has nothing to do with us would be a catastrophic mistake. If we want to help in a humanitarian aid capacity, help with refugees fleeing to Lebanon and Turkey, provide food, water and shelter to those who explicitly ask for our help, I'm behind that. To an extent.
Apply some diplomatic pressure, refuse to do any business with Syria and encourage other nations to do the same, and let it play out. They're a sovereign nation, and we're beholden to international law regarding attacking unprovoked. Let the international body actually tasked with these decisions do its job, and if Russia and China want to block it, so be it, that's on them.
For a nation as bogged down by debt, domestic issues and other lingering entanglements as the US, another murky, debatable engagement makes zero fucking sense.
Please don't do this.