I will be in Shanghai during the National Holiday. I would like to go to Suzhou for 2 nights to see the gardens on Oct 5 and return on Oct 8. Will I have difficulty purchasing "D" or "G" train tickets if I go to a ticket office 3 days before I want to go? Would it be better to go by bus? I will be in Hangzhou before I arrive in Shanghai. Can I purchase the tickets to Suzhou there or are they only sold in Shanghai?