I went to Kawagoe and loved it. It was one of my favorite experiences in Japan. If you want an interesting way to introduce a child to temples and shrines, it's a great place. Kitain Temple is set up like a museum, with interesting things in all of the rooms (not bare like the other temples I walked through in Japan).
Hikawa Shrine is entered by walking under pinwheels, and it has a fishing "game" and a place to float things down water.
The best spot of all was Kumano Jinga shrine, which has crow images everywhere. There are colanders and water where you wash your money, and a ring toss "game."
Also sweet potato snacks (everything you can imagine), candy alley, and the Kawagoe Festival Musuem.
The only downside is that some of the major sites are spread out. There's a bus loop that travels between them.