I'm not sure how "good" these suggestions are but we've used them in the past.
Esther and the King by Kelly Pulley Though I changed the wording used to "read" the story. See here for words I used. (Scroll to the bottom.)
The Story of Esther. by Patricia A. Pingry. (ISBN: 0-8249-8420-X) Also "rewritten" here.
Hope this is helpful.