I visited Bailixia during the National Day holiday, and it felt completely different from summer. We left Beijing in the morning and arrived in about two hours. I recommend not sleeping in; if you arrive around 7 am, there's still parking available, but by 9 or 10 am, the cars are lined up outside. The canyon in October already had a touch of autumn; the mountains were a mix of yellow and red, with steep, rocky cliffs on either side, making for beautiful photos from every angle. The key was the coolness. While the sun was blazing outside, a gentle breeze once you entered the valley was incredibly refreshing. It got a bit chilly after walking for a while, so bringing a light jacket was definitely a good idea.
We entered through Haitangyu and exited through Shixuanxia. There were streams along the way, but the stone paths were a bit slippery, so wear non-slip shoes. The narrowest part of Yixiantian (One Line Sky) requires you to squeeze sideways to get through; it gets crowded during the National Day holiday, so don't stand there endlessly if you want to take photos. The Heavenly Ladder steps are quite strenuous, so I took the cable car up (50 yuan one way), which saved me the effort. There's a high-altitude bicycle show at the summit in the afternoon; if you happen to catch it, just take a quick look—it's quite thrilling. A leisurely stroll through the entire area takes three or four hours without getting tired. Things tend to be more expensive during holidays, so bring your own water and snacks. Anyway, if you're looking for a place that's not too sunny during the National Day holiday, where you can stroll around and enjoy autumn scenery, Bailixia is a good option, but you should go early.