Spend day 4 exploring Tianzi Mountain and Yuanjiajie Scenic Area, both within the Zhangjiajie National Forest Park. Tianzi Mountain offers breathtaking views of towering sandstone pillars, lush valleys, and mist-covered peaks. Take a cable car ride to the summit and hike along the various trails, immersing yourself in the stunning natural beauty. Next, visit Yuanjiajie, famous for its inspiration of the floating mountains in the movie 'Avatar.' Explore the 'Avatar Hallelujah Mountain' and enjoy the picturesque scenery.