Very peaceful, bring a jacket!
We were able to get a site further back from the entrance, so traffic was to a minimum. There was occasional cars and OHVs back to some of the trailheads, but otherwise we were pretty much by ourselves!
It did get pretty cool at night, and our kids definitely let us know about it. Luckily we have extra blankets to insulate their bags and another person in our party had a small heater. But even in July, plan for cooler night time temps and rain!