I endorse Ray's comments. There is so much here to do you are not allocating much time. Although Quedlinburg gets the tourist guide headlines, in part due to its very old houses, I find compact Wernigerode and its slightly newer timber framed houses more visually attractive. For such a brief visit I would stick with Wernigerode as a base. The Tradzug recently has been a disappointment with ordinary coaches in the formation and any 2-10-2T used. So no different to a normal train, yet a premium fare. Ray points out the useful buses but do note the Sat/Sun bus service is poor - rail is OK though, 7 days per week.