Our girls are 13 and 10, but our son is grown and gone. He camped with us up until he left for college, but would come back for weekend trips here and there. Our girls started camping at 3 months and so far, they like to help plan all of our trips. If it seems there will be nothing for them to do, they will take a friend with them to add some fun. It's always enjoyable for the girls to take novice campers with them. They get to teach them lots of things, like how to make s'mores, build a good fire, identify constellations, etc.
We try to find campgrounds/resorts that have things for for them to do and we also have a couple of tandem kayaks that we use if there is water around.
