I have scheduled to visit Dujianyan and also Mount Qingcheng from Chengdu end of october,2016

Can you give your advice which place to visit first, and which is more convenience as I planned to stay overnight either at Dujiangyan or near to Mount Qingcheng since I would like to book the accomodation before I travel. I also wish to know wether bus or train from Chengdu arrive Qingcheng station first or Dujiangyan ?

Thank you. Mr Lee