Northerner,
What is often forgotten is that traditional storytelling in the tradition was an adult activity and it really doesn't matter what the subject is.
MacColl used to tell of the time he and Peggy were recording Scots Travelling women in their home in Beckenham and when they started on ghost stories, the women wouldn't to go the few yards to the toilet on their own, they had so scared themselves with their tales.
We caught some of what must have been the last of the big storytellers here in Ireland and their stories ranged from a few minutes long to, in one case, two hours plus. These were Jack tales, ghost stories, wonder tales, trickster yarns, fairy stories and Fenian yarns.
The thing we noticed with all the tellers is their complete lack of self-conciousness and the ability to suspend their own logic while the story lasted, no matter what the subject.
None of them felt the need to put on funny voices or to use dynamics.
This, I believe, is the secret of good storytelling.   
Jim Carroll