"a bug's land" in California Adventure is a great spot for your grandson. This area is specifically designed for little ones. Fantasyland also will appeal to him. Keep in mind that the dark rides, at least for my kids when they were little, were not scary because of the darkness, but because of the loudness. On Pinocchio's Daring Adventure, the noise from the carnival rides made my son plug his ears and hide his head! Wait in that line for Dumbo - you will never regret it! Also, keep in mind that part of the Disney experience is not an attraction. The characters, the parades, the shops, the music and sights in every area, are so wonderful, that you will enjoy sitting on a bench and watching him dance and have fun! Enjoy!