i find this discussion interesting but lacking in perspective.
everyone is looking to seattle, paris, etc etc without realizing that a successful march did take place in Chicago and attracted about 100,000 people and had the same route the the one on march18th.

Remember the immigrant rights march? People showed up with or without busses. Crowds were huge from union park to federal plaza. Immigrants of every stripe walked, drove, took the bus, rode bikes to this protest. There were no "green zones" or prescribed list of chants or anything else.
There was an idea, an urgency and many groups showed up.
and while i was stuck in traffic while thousands of marchers were going down Jackson, there was something different about them.
You see, they looked happy! They looked empowered. They didn't look bored. They didn't have drums or noise makers but their spirits seemed high and they were all excited to be marching.

So instead of looking at seattle, maybe an example of effective march is right here in the city. While they didn't have red flags and newspapers for sale, they organized a pretty awsome action.
Not matched by any other coalition ever.