I use the bible. LOL....Ok that was not a fair answer, but that's what I ultimately turn to.
I am the main spiritual mouthpiece in my family, or they might ask me a question from time to time, but we use what I like to call "catalyst" for spiritual discussion. News, gossip, movies, popular culture, life events, even sermons at church, all of these things I use to start conversations and weave in spiritual insight. It's tricky, but I've gotten better with practice.
I have a wife, a 10 and 13 year old. We are a Christian house, but I'm not so naive to think that just because we go to church and behave as Christians that my family does not struggle with their own worldly issues. So, I try to tap into the hearts and minds of my family to address those things from a biblical perspective. It's great when I can just rattle off scripture, but often times I leave the conversations having to do a little research and come back to them.
My wife might tell me about something that happened at work, or how she's feeling about an issue. My kids will do the same. They drop little insights into there soul all the time. So I try to pick those up, examine them, and apply them to Gods word. I may be able to do it very quickly and respond to them, or I may take some time and get back to them.
I find this type of devotional very powerful, because it's tailored to my family. My kids seem to appreciate it more than just having a sit down study, because it means more to them.