Jon Bloom at Desiring God gives Six Benefits of Ordinary Devotions. Good to pass on to our children.

Soul Exercise (1 Corinthians 9:24, Romans 15:4): Devotions are like exercise for our souls.
Soul Shaping (Romans 12:2): The body will generally take the shape of how we exercise it. Running shapes one way, weight training shapes another way. The same is true for the soul.
Bible Copiousness (Psalm 119:11, Psalm 119:97, Proverbs 23:12): A thorough, repeated, soaking in the Bible over the course of years increases our overall Biblical knowledge, providing fuel for the fire of worship and increasing our ability to draw from all parts of the Bible in applying God’s wisdom to life.
Fight Training (Ephesians 6:10–17): Marines undergo rigorous training in order to so ingrain their weapons knowledge that when suddenly faced with the chaos of combat they instinctively know how to handle their weapons.
Sight Training (2 Corinthians 5:7, 2 Corinthians 4:18): Jesus really does want us to see and savor him. Savoring comes through seeing. But only the eyes of faith see him.
Delight Cultivation (Psalm 37:3–4, Jams 4:8, Psalm 130:5): Devotions are one of the ways we cultivate delight in God.

Read this whole article and then read for family devotions. These same principles are true for family devotions.