Well, this was a different and rewarding experience, and certainly an extreme day hike – flying from San Diego to Washington DC to walk 100km (62.5 miles for you metrically-challenged) along the Potomac River.  The walk (hike, race?), sponsored by the local Sierra Club chapter, started close to the Watergate complex (yes, that one) in the Georgetown section of Washington DC, and ended up many hours later a couple of states away at Harpers Ferry.