Went with my wife and 3 kids (14, 12, 10) to the AAA convention in Denver over the weekend. 10 year-old went into camp quest, the other two came with us to the "adult sessions". If you have a kid of similar age our oldest two, all i can tell you is that they both enjoyed it immnensely and we stayed as a family for every single talk (we thought originall we'd just hit a few highlights). Every single talk was awesome, especially pz, jessica ahlquist, hemant mehta but it every single one of them was great. If you have a chance to go such a convention, I urge you to do so!
My son got himself a picture with PZ and Hemant, My daughter has a pic with PZ (all on facebook already). My son is already researching into which convention he wants to go to next!