Roughly an hour's bus ride north from Yangshuo will take you to the small fishing village of Xingping. It's just south of the karst bluff viewpoint imprinted on the back of the 20 RMB note. Alternatively, you can reach the quaint village by haggling with the endless array of touts and their bamboo rafts (or it's modern PVC-replica version) in Yangdi or even further up the river and coasting south along a wonderful area of the Li River.
When I traveled, I opted to bamboo raft for a smaller fee from Yangdi down to Nine Horse Frescoe Hill and hike through farms and along the interior road the rest of the way to Xingping. It took a few hours between walking and a nice stop for lunch at a riverside cafe, but the scenery was quite rewarding.
When you finally reach Xingping, close to the waterfront and guided by a few signs around the back of several buildings (ask locals if you get lost and just point up) there is the trail to Lao Zhai Shan - a karst peak with one of the best views in the entire Yangshuo region. Climb up the 220 meters or almost 1160 steps to the top (give yourself a good 45min or more) and marvel as the sun sets on the river scenery, village below and seemingly endless array of karst peaks fading into the distance.