mount whitney is the tallest peak, in the lower 48, at 14,505'.  It is a 22-mile round trip hike requiring a hiking elevation change of 6,100' from trailhead to summit.  I liked this hike for numerous reasons: the sheer physical challenge presented by completing the climb in one day (departed the trailhead at 3:24 AM, using a headlamp, and returned to the trailhead at 5:07 PM), the beautiful star-filled sky as I started the hike in the dark, the amazing views as the sun rose over the valley, and the gorgeous views from the summit.