Right now, the North Kaibab trail is closed for repair at the Redwall Bridge due to a rock slide and the trail from Pipe Creek to the silver bridge is also closed for repair.

http://stgeorgeutah.com/news/archive/201...s/#.WORyCjvyuM8

My husband and I have done the R2R2R many times, starting from the south rim, but we stay overnight at the north rim before hiking back to the south rim. We think the Mt. Whitney day hike to the summit and back down is harder because of the altitude.