I think they'll be fine. My parents used to leave me home alone at 9. Then again, that was the 90's, and the rules were pretty strict. All I did anyway was homework and tv. haha I was able to roam Disneyland by myself when I was 14. This was before 14 year olds had cell phones, so I was without... instead I was able to do whatever I wanted with my friends and other family teens, and we had to meet up with all the adults and littles at the castle before the fireworks. You know your kids best, you trust them, and they've shown themselves responsible before... maybe try it out, but stick to certain rules. Our rules were things like "no park hopping" "stick together" etc. Or, you can stick to a certain land... like have lunch at Paradise Garden Grill, and let your kids ride everything in Paradise Pier. Have a great trip!