Even during what would appear to be at the period of peak attendance it's just not that crowded. Check this CNN video at about 30 seconds. Pay attention to the grassy area on the left, next to the reflecting pool. It's just wide patches of grass. And then check my post from yesterday.
Roughly the same shot can be seen at this C-SPAN screencap:
And Andrew Berman states the main problem: "I still have not found a good overhead shot yet ..." Exactly. William Teach predicted that we wouldn't see any overhead shots, and we won't, unless a tea partier cruised up to the top of the Washington Monument to snap a picture. If one become available it would go viral big time. See a report from both Glenn Beck's and "One Nation" at Just a Conservative Girl, "8/28 Crowd V. 10/2 Crowd See for yourself." And at Lonely Conservative, "Rally for Socialism Fails to Draw Much of a Crowd." Plus, at RWN, "Lefty Rally at Lincoln Memorial Gets Glad Handed By Old Media, But Event a Bust." And Nice Deb has the most comprehensive roundup of the day, "One Nation of Moonbats March on Washington."