Hey Jim,
My family spent spring break at the Myrtle Beach KOA and we really loved it. It was very family friendly and a nice, safe environment. There is a nice pool and sprayground, fishing on site, and a bounce pad. It is a very shady campground which will be nice for July, and the staff is super friendly. The KOA is about two blocks from all of the fun craziness of the boardwalk but it feels a world away. Here are pictures and a review from our blog. Our kids are younger than yours but I am sure that they will love it as much as we do. If you have any questions please ask.
http://livelylittlecampers.com/2014/04/how-we-roll-when-a-campground-rocks-myrtle-beach-koa/
