Michelle, Wow, what a great question!! I think a good conversationalist is similar to a great storyteller. The topic would depend on the audience however, the conversation should be one that allows the listener to think about what is said as well as keep the listener captivated with stories that relate to the main idea.
When the roles are reversed, the first listener now the conversationalist has to keep the conversation on topic and still captivating.
The listener must actually listen and the conversationalist must keep the conversation on topic as well as draw the listener in. Both while switching roles, should share ideas and keep the conversation going.
By the way, I love the new profile picture!!! :D