So far my favoriate hike has been the Otter Trail in Tsitsikamma National Park (South Africa). It is only 42.5 km (26.4 mi) with nice places for you to stay for the 4 nights it takes to complete the trail. There is a limit to how many people are allowed to hike and the spaces fill up soon so be sure to book ahead through South African National Parks. This post provides a nice description and this one does too.
Photos: Charlane Brady & Aaron Danzer