classic dayhike at Haleakala:
park at the Halemau'u trailhead.
hitch a ride to the top (theres a turnout on the road near this trailhead specifically so drivers can pick up people doing this hike)
walk down the sliding sands trail.
come back up the halemau'u trail.
I don't remember how long it was. 15 miles maybe? *edit-- that map says 12ish*
It's a really pretty hike.
you can make it longer by traveling further East along the sliding sands trail before cutting over.
http://www.nps.gov/hale/planyourvisit/u ... ng_map.pdf
I don't know anything about the trail that climbs Haleakala from the southeast. We tried to drive over that way, but the road is complete shit so we decided to eat fried chicken and snorkel instead.
http://www.summitpost.org/route/162166/ ... trail.html