I actually participated in the national Day of Reason 2 or 3 years ago in PA.  A local group (PAN--Pennsylvania Nonbelievers) set up a table with literature about atheism, humanism, etc (with written permission) inside the capital building on the same day as the National Day of Prayer.  We talked with a number of people there, including state reps, visitors, and a few fiery evangelicals who worked there.

 At one point, a particularly zealous representative ran across us and was quite beside himself.  Ge told us that we could not be there and that he would have another table for people not trying to spread the lies of evolution and secular evils.  A couple of hours later, a woman set up a table with Creationist and Christian literature, with whom we had a cordial, yet passionate discussion with.  It drew a bit of attention, us both being there, and we were told by some staffers taht they felt pity for us, and offered us literature (while rejecting ours).

 Quite a day, that was.  I'd do it again.

Atheist Blood Drive on May 3rd: http://www.atheistvolunteers.org/