I don't think you're going to get much argument here. But the wild card in this entire situation is the fact Obama has nothing, absolutely nothing to point to as a win on foreign policy. And the fact the Russians, specifically Putin, are basically goading us into doing something is the key element here.
Most of the people on here agree that we have no interests worth fighting for in the Ukraine. But we also had little interest in Libya. And Syria for that matter before getting trumped by the Russians.
I know how much hardcore conservatives dismiss him, but I think Fareed Zakaria offers an interesting perspective on this issue:
Fareed Zakaria: America plays its role in a changing world right - The Washington Post
We can disagree about Obama's overall foreign policy. For instance, I agree that Syria might have been handled differently (although you should recall that there was also a big stink about how billions of dollars had been used to launch missiles in Libya, and this was something weighing upon the administration's mind regarding Syria).
The key thing we should take into consideration here is that Putin has absolutely nothing to lose. He doesn't give a **** (as you've admitted yourself) about the international community or his image, internationally. This is a much different situation than what Obama faces.
Now, here are some things we can reasonably do, and we'll see how Obama handles this in the future:
1. The EU can back off from trade with Russia.
2. The US can reinvigorate talks about missile defense systems in Eastern Europe once again (which I think we pulled out of because of Russian demands concerning their supply of natural gas, oil, etc. I could be wrong here though.)
3. The G8 can kick Russia out, or force some limited membership role.
4. Economic assets of Ukrainian (and possibly even Russian) oligarchs can be freezed.
5. Flying unicorns can invade Putin's Russia and overwhelm him with magical flower power.
But, to be fair, we'll see how Obama does in the coming days. I still think it's too early to tell. But these are measures he should pursue, minus number 5, obviously.