I love how people act like Lelouch is some sort of bloodthirsty, innocent-ignorant terrorist who just wantonly gets "thousands" and "millions" killed. He actively comes up with plans that minimize death counts, as opposed to Britannia, that murders thousands for fun and profit because their elitist, power-mad, cowardly shits.
Other then, admitedly, killing a bunch of scumbag criminals in place of the police, every other military and violent action undertaken in season one was started by THE BRITANNIANS, until Lelouch has his forces attack Shikinejima near the very end of the seas. A deserted island save for Britannian troops. And the only action he instigates after that is the season finale. The violence is Britannia's fault for the most part, not Lelouch's.
Furthermore, Suzaku's problem with Zero (until he gets Euphemia killed that is), is not his plans or his actions, or even his violence (he comments several times over the course of season one that he respects, understands, and even sometimes, when it saves his friends where he failed to, even appreciates Zero and the Black Knights and their methods. His problem is that he insists that Zero is winning using "the wrong channels".
He seems to mean that because Zero is not a legitimate political power, any action he undertakes to save people, however good the intentions, makes him a terrorist. Although, I personally concur that no matter WHAT Zero did Suzaku would take issue with it because, as some Anon pointed out above, Suzaku's emotional trauma and false persona requires that Britannia stay in control or else his psyche would break completely.