I used Kepler Maps working with the database of the Library of Congress Slave Narratives, focusing on the place of birth of each informant and where they were interviewed for the project. Working from the assumption that the place of interview–while important–was probably not where the person lived when he/she was enslaved, I found it useful to include the birthplace information. Of course, not all informants necessarily remained at their birthplace through their period of slavery but at least this gave a broader picture of the experiences of the informants and how broadly through the South they were originally spread.
I found the Kepler software not particularly easy to use and somewhat clunky particularly when it came to exporting maps and also the need to reload the database each time I returned to the software. I suppose this might be due to its online, open nature; perhaps there is a downloadable version that enables you to save personal maps and data more efficiently.
For a new user, I would plan having enough time to complete a full map and save it in some form in one sitting to avoid having to reproduce work already performed. I also imagine that if cost were not an issue there might be easier-to-use mapping software that would allow for more flexibility to the user.