what is the best itinerary if i wanted to visit Zhangjiajie & Fenghuang from Changsha in 5 days?

You are suggested to visit Fenghuang Ancient Town first and then ZJJ Scenic Area.
1. Take bus from West Bus Station, and arrive at Fenghuang Bus Station. The schedules are 09:00, 10:40, 14:20 and 17:20. Then hire a private car to get to the scenic area.
2. From Fenghuang Ancient Town to ZJJ, take direct long-distance bus. They depart at 09:00, 10:00, 12:00, 14:00 and 15:00. After that, take a taxi or share a private car to arrive at the scenic area.