Distance: 8.5 miles (13.5 km) one way
Elevation Range: from 4,000 feet (1,220 meters) on the valley floor to 7,200 feet (2,200 meters) at Glacier Point
Total Elevation Change: 3,200 feet (975 meters)
Map Notes: The red line marks the path of the Panorama Trail. The yellow line shows a pair of alternate routes along the John Muir Trail that allow you to avoid the steepest parts of the Mist Trail.
You can hike the Panorama Trail in either direction - or both, if you find the Yosemite air especially salubrious. If you start at the Glacier Point trailhead, marked by the leftmost pair of giant green hikers, you'll be going downhill for most of the route, with the exception of some climbing just after you cross Illilouette Creek. If you start in Yosemite Valley, you'll be hiking uphill most of the day.
Whichever direction you go, be sure to stop and take in the Panorama Point vista, marked here by the blue balloon. It's a short detour - a hundred meters or so - with spectacular views. The trail is unsigned, so you'll need to be looking for it.
The bottom section of the trail merges with the popular Mist Trail, which includes Vernal and Nevada Falls (the green balloons show their locations). The stretches of trail beside the falls themselves are among the steepest in the park. If you've got various body parts threatening to mutiny against your brain and elect a new one that's not so demanding, you can give them a break by taking the John Muir Trail (the yellow line) instead. It's longer and less scenic (except for one fabulous view at the very beginning), but not so steep as the Mist Trail proper. If you've recovered by the time you reach the fork in the Muir Trail, take the right fork, which comes out above Vernal Fall and will let you experience the mist-drenched staircase descent beside it; if you're still suffering, take the left fork, while reattaches to the Mist Trail just upstream from the Vernal Fall footbridge (this assumes you're hiking the Panorama Trail from top to bottom, by the way).