Here is a list of the books I read to the kids during our morning prayers.
Almost every morning, but especially during the month of November, which is dedicated to the suffering souls, I read a story from Purgatory Explained. This book has some very powerful stories, and the kids are fascinated by them. Our daughter Cecilia picked her Confirmation saint, Saint Christina the Astonishing after hearing the heroic penances she did for the conversion of sinners and the souls in purgatory.
I try to read Lives of the Saints for Every Day of the Year to them every day, if not at least during major feast days. The stories aren't very long and they're very easy for the children to understand.
The Mass Explained To Children is a lovely little book to have around, especially if your family attends the Traditional Latin Mass. I don't read this one every day, but it's the perfect book if you are doing a unit study about the Mass.
The Imitation of Christ is in my opinion, the best spiritual book to read to children. I try to read this to them at least every other day or so. We have 5 copies of it scattered around the house. My wish is to have each of the kids read a chapter of it in their rooms before they come downstairs for the day, but so far I haven't been able to add that to our morning routine.
I've had 2 copies of My Path to Heaven: A Young Person's Guide to the Faith for a very long time, but I haven't taken the time to complete the retreat all the way to the end. I did the first 2 lessons, but I didn't keep up with it. Maybe I'll do the retreat with them during Lent next year. The pictures are absolutely beautiful and the questions at the end of the lesson really make you think.