Just glancing at some news archives from early 2003.
Here's an anti-war protest from April, 2003 in Washington, DC with an estimated attendance of around 100,000 people.
Here's another anti-war protest in New York with numbers ranging from 40,000-100,000 people.
Here's one at the U.S. Capitol from January, 2003 boasting tens of thousands of people.
I'm not a huge fan of protests as a means of delivering political messages (at least now in the intertubes age), but none of those protests received anywhere near the establishment media attention as these comparatively dinky tea bag groups. One thing is for sure: the anti-war protests certainly didn't have an entire cable news network dedicated to promoting and covering the events.