Visited with my 8 year-old last summer. This campground is rustic (hello pit toilets!) and there wasn't a camp host onsite, but I'd go back again because the stream and falls are gorgeous, the sites are spacious, and the Newberry Volcanic Monument has so much cool stuff!  (We loved the Obsidian Flow!) It's also a nice break from the more popular campgrounds that are overrun with obnoxious Portlanders (I say this as an obnoxious Portlander).  In August, it was warm during the day and cool at night. 

BYO water, and get gas in Bend. If you're desperate like I was, Eastlake Resort has a single gas pump that sells the most expensive gasoline I've ever purchased.