UPDATE: I agree with Josh Marshall that turning over the chemical weapons for destruction is fine as an alternative, and IMO much better than a strike. If Assad only plays along for a while and then refuses, we could reassess whether to strike then or wait for him to use them again.
I'm glad that Obama is going to Congress, and he obviously shouldn't move ahead if Congress doesn't pass the resolution. The US moves too slowly on domestic matters. We have at times like World War II, Libya, and Syria itself, also moved too slowly on military involvement overseas. The more typical pattern though is for military involvement happening too quickly and on false pretenses. Getting Congress involved is a good idea in the long run, even if it results this time around in the mistake of tying Obama's hands. Waiting so that we can go from 97% sure of what happened to 99%+ sure is also a good idea.
Lots of stupid arguments being made on both sides. The antis say that anything short of overthrowing Assad is a failure as a deterrent and that a military strike will harm domestic programs at home. The pros say that failure to strike puts the US in immediate danger, and continue with the old chestnut of conflating chemical weapons with nuclear weapons as "weapons of mass destruction." The antis make sadly laughable claims that diplomacy is going to do anything about chemical weapons or about the problems in the Syrian opposition (Rep. Chris Smith says a military strike won't deter Assad but Smith's proposal to eventually set up a war crimes tribunal may help). I heard another Republican Congressman criticize Obama for not attacking when the previous, ambiguous chemical weapons uses occurred, and then say he'd vote against authorization.
The key issue is that the chemical weapons use and what to do about Syria overall are separate issues, despite the desire of extremists like McCain to tie them together. Obama seems to understand that. A reaction by the US and France to the chemical weapons use, either a military or non-military reaction, would succeed if it leaves Syrian decisionmakers thinking that doing it again would not be in their best interest (or if it really was just a mistake, then realize they had to get their system under control). I just can't think of a non-military reaction that has that effect.
I think it's not ridiculous to argue that the outside world should do nothing (sorry, do diplomacy only) after further chemical weapons attacks - we can't solve all the world's problems - but I think on balance it's a bad argument. I'm guessing that if the authorization goes down, Obama will just wait for further attacks, and then most likely strike without asking Congress (even though he should ask Congress).
Yes, the US is being hugely hypocritical in opposing Assad while doing nothing elsewhere, like Bahrain. That's not a reason to do nothing but instead a reason to fix our act in Bahrain.
For those who think the current bad news in Libya proves our involvement there was a mistake, my bet offer is still open, and updated.