DriveThruRPG has created a page listing a large number of games they offer that are great for playing with young people. They are encouraging people to teach games to their children and play with their families. It's good for their bottom line, and it's also great for our hobby community. I think this page is a great idea, and they have many ideas, choices, and discounts. Since most of their titles are available in less expensive, digital formats, they're even cheaper and easier to manage.
I especially like Adventures in Oz, Argyle & Crew (sock puppet adventures!), Faery's Tale, Fate, Little Wizards, Mouse Guard, Teenagers from Outer Space, and YARR! Rules Light Pirate RPG, and they have many more titles I need to investigate. I'd love to know which of these games you've tried and how they worked with people, young and not-so-young.