My son has been riding with me for years. AGATT of course. Now that he's 14, he has his own dirt bike and will probably ride the KLX to high school when he's old enough.
Between now and then, he rides pillion with me quite a bit. It's a great opportunity to get him thinking about riding proficiently. Our conversations go a lot like this, "Hey bud, where do you think the threats are?" He's learning to see that car at the light in front of us that might turn left, or the chick in the SUV yacking away on her cell phone in the next lane.