We do Beautiful Days festival every year with DS's who are now 12, 9 & 4 yrs, they love it and it's now part of their summer holiday routine 
Apart from a Levellers mad (still) husband, it's fantastic for the kids, so much to keep them busy and a fab family vibe throughout the weekend.
Am always looking for more kid friendly camping hints as we're learning each year as we go along, especially with the meals..fed up with the same old sausage & bean menu!
All suggestions gratefully received 