I agree with you about Occupy. I think a big problem is that some at the Occupy events (a very few, but that's all it takes) are actually eager to be violent: throwing bottles, openly scuffling with cops, etc. They argue that they wanna tear down the system by force... "start a revolution" or something? *eyeroll*
But it's still stupid because the way to maximize the success of any protest is to operate in the manner that allows it to continue: as you said, peaceful demonstration. Advantages:
1) keeps them as safe as possible under the law.
2) minimizes the ability of police from using those violent elements as an excuse to say, tear gas the entire area, shoot people in the face with beanbags, use downed protesters as bait to lob in gas grenades, yadda yadda.
3) avoids giving opponents PR ammunition to discredit you en masse in the press to readers who might otherwise be supportive.
So as _effective_ protests go, the people harassing or outright attacking the cops are making it all far less effective. At _best_ that just makes for extremely nervous, jumpy cops. Not a helpful thing for anyone concerned.
I don't mean to automatically assume in my 3 points above that the authorities and cops are not well-meaning... but to sum up, nobody on any side should be giving anybody else an excuse to feel justified in use of force.
There are tried-and-true protest methods that have been used to great effect in America and elsewhere. Do we really need to reinvent the wheel all over again -- find this out the hard way?