When looking for kids sleeping bags, the most important thing to look for is something that will fit your child well and will provide adequate warmth for the temperature you are going to be camping in.
If you are just planning on camping during the warmer summer months, a simple sleeping bag from home (maybe your child's Star Wars or character sleeping bag that they have around the house) could do just fine.
If the nighttime temperature is going to be below 50 degrees or so, I recommend looking for something that will keep them warm, as you do not want him or her to not be able to get a comfortable night's sleep.
Some of the more popular manufacturers of these camping products include Eureka, Slumberjack, Marmot, Kelty, Coleman, and the North Face. You can find products from all of these companies below...