I am planning to go to Huanglongxi from Xinnanmen Bus Station (or Chadianzi, still undecided).

First of all, the trip takes around an hour.
From Xinnanmen Bus Station: The bus schedules are from 07:30 to 17:10 at intervals of around 30 mins. The ticket fare is CNY 16 per person.
From Chadianzi Bus Station: The buses are available from 06:50 to 19:00 with the frequency of half an hour. It costs CNY 15 per person.

Thank you so much!