Good devotion books are so helpful in creating regular and engaging devotion times for families.  You can and should simply read the Bible with your family.  The Bible covers every topic that is necessary for shepherding your children in this fallen world.  However, it's also beneficial to have devotion books that include pictures to capture the attention of the youngest family members, and books that include rich life applications that we might not think of on our own.  

Family devotion time is my favorite time of day.  It's the most important thing we do as a family!  Going to the park with your kids is wonderful, playing games together as a family creates great memories, but teaching your kids about how awesome God is, is the only thing that you will do that has eternal consequences.  And this is certainly not limited to evening devotion time!  Teaching your kids about God happens all day long.  God reminds us, "And these words that I command you today shall be on your heart.  You shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise."  Deuteronomy 6:6-7