Development of public support against greater security at the cost of freedom is the only way to make meaningful change. Yes, marches/demonstrations can be part of this. But small demonstrations do not alone capture the public's interest. One must capture the public mind--and that means informing the public and winning their support of having less "security" where weaking or violating the protections of their basic rights are concerned.
Right now, as various polls have showed, far too many Americans desire the feeling and theater of security. They are content to be invaded at airport security because eventually they can still fly. They are content to have their communications slurped up because they can still send that email and make that phone call.
It's not until they're staring at a public fountain from which they are not able to drink because it has a stupid printed sign above it that says "Whites Only" that the public will accept that things have gone horribly wrong.
I think demonstrations would be excellent to see, but not if they're anything like the Occupy movement, which the wider public opposed against their own self interest. It is very difficult to get the public's attention when they do not feel the effects. The public is rather shitty at evaluating and appreciating things in the abstract. Demonstrations that are massive and concentrated would have a much more significant impact. Think of the Civil Rights March on Washington. That level of mass and concentration. Doubling it would be even better.
And yet, even that basic right to protest has been severely weakened by the fact that one must get a permit to protest in many of the locations that would be tactically good choices. This is madness. The 4th is not the only Amendment that the People have allowed to be weakened over the last two centuries.
Americans have become very lazy where protecting their rights are concerned, because the vast majority of Americans do not participate in protecting those rights when they are violated against minority factions.