As far as Dickinson is concerned, I have always found it interesting that religion and the role of the father appear. Her choice of diction really shows her stretching her wings, subtly, as a woman in the world during the mid 1800s. Yet there also seems to be this tension against men with power.
Also just by her actions. She was known as being a recluse or hermit, but why? She wrote once that she keeps the Sabbath by staying at home while others go to church. I think it may be far to say that her withdrawn actions shows a direct disenchantment with society, especially the institution of religion. She was religious, she grew up around it, but was also very educated. Religion was a personal experience for her, when people were caught up in the fervor of revivals, she was resigned.
I am not totally familiar with the recent book published with her correspondences, but I bet that has a lot of answers in it.
One of the shared themes in the thought of Whitman and Dickinson is the disenchantment with traditional society and its institutions. To a great extent, both thinkers lived their lives with the idea that there is an element of non- conformity which is not present, but needs to be. For example, Whitman believed that the unique character of America cannot be found in the existing social institutions, but rather has to be found in the domain outside of it. For example, in "I Hear America Singing," Whitman does not extol the virtues of the social elite or the domain of existing power, but rather in the common individual, the working man and woman. Throughout his poetry, Whitman seeks to travel the path that is not worn and, this disenchantment with "what is" helps him to envision what can be. Dickinson is much the same way. Her introspection is done, in part, because modern and established society does not permit it. For example in her poem, "I'm nobody! Who are you?", Dickinson explores the idea of the "social nobody" and the individual who is marginalized by the accepting social order. This reveals her fundamental disenchantment with the existing social institution. She also explores the rejection of traditional social values, such as the view and perception of death. For example, in her poem, "I Could Not Stop for Death," her conception of death is almost a warm and tender companion, as opposed to the accepted vision of death which is far more harsh.