In my opinion, two of the best books to read to your children--outside the Bible itself--are The Jesus Storybook Bible and The Big Picture Story Bible. The author of the former acknowledges her debt to Tim Keller; the author of the latter specifically thanks Graeme Goldsworthy.
My 3-year-old daughter loves both of these. They have great illustrations, and they accurately present Scripture as a unified story of redemptive history that culminates in the person and work of Christ.
Both highly recommended.
Update: I should also mention a book by Starr Meade (a gifted Reformed writer): Grandpa's Box. It's for an older age group, but it seeks to tell the story of redemptive history in an imaginative way. There is a study guide available as well.