http://www.nps.gov/mall/planyourvisi...-questions.htm Seems they do these tours every Saturday and Sunday so that's convenient, but each tour apparently focuses on a different theme. (Note: I was typing this as NY was editing her post...)

Do we want to try to pick a day with a theme that's interesting, just pick a day and have it be a surprise, or not worry about learning anything new and just go on our own route as our own group?