Where to go during Golden Week this year?

I am living in Beijing and I am desperately trying to find a destination (for 5 days) to avoid crowds during the Golden Week (1st to 5th October).
I like natural sites better than cities, and I don't mind taking overnight trains to travel. I speak Chinese and am not afraid to try less frequented paths! (I was thinking about Inner Mongolia maybe?)

I would be very happy if you could give me some ideas!
Thank you so much in advance