The Petit Grepon is one of the most classic alpine peaks in Colorado. The South Face is one of the 50 Classic Climbs with good reason - the rock is excellent, the exposure stunning, the steepness is impressive for a moderate climb, and the summit is the best in the park.
Approach: Park at the Glacier Gorge parking lot off Moraine Park Road. Hike up past Loch Vale, and follow the trail to Sky Pond. Sky Pond is one of the most spectacular places in the park - Cathedral Wall in on your left, the Taylor Glacier Headwall is directly in front of you, and Sharkstooth, the Petit Grepon and the Saber loom on the right. The Petit Grepon is the middle tower that looks like the Eiffel Tower.
Resist the temptation to scramble to the base too soon. Walk along the edge of Sky Pond to the far end, and look for a climber's trail heading through the talus. This trail deposits you right at the base of the route. The approach is about 5 miles, and takes 2-3 hours.
Descent: Walk along the summit to the end opposite Sky Pond. Make two double rope raps down towards the gully between the Petit and the Saber. Stop on a large ledge system above the gully and scramble 3rd class along the ledge system towards Sky Pond. 3-4 more double rope raps down the South Face leave you very near the base of the route. This rap descent was there on July 4, 2001 and all anchors were bomber. If the anchors are for some reason gone or look sketchy, rappel into the Gash - a nasty snow and talus filled gully on the other side of the Petit Grepon from Sky Pond. Descend the Gash and then head down a trail that eventually hooks up with the main trail. This puts you very far away from Sky Pond, so it is best to bring everything with you if doing this descent.