One of my family's favorite places to go camping. Tons of room for the kids to roam and explore, so many playgrounds they're almost a tripping hazard, and free firewood. We like camping in "Deer Lake" #s 405-408 and "Timberlake" #s 315-318. (Deer Lake is electric, Timberlake is not.)
Water spigots are plentiful, and the campground has maybe a dozen large pavilions you can reserve for free, or scurry into in case of a pop up shower. I've already mentioned the playgrounds, and in addition there's a waterfall, old steel bridge with a connected spiral staircase, and even a village of tiny houses. They recently installed a BMX track, but made the mistake of using large gravel to "pave" it--it's too soft and nearly impossible to ride on quickly.
The only real knock I can give the place is that the sites are REALLY small, and some are not so level--I strongly advise you get at least two to gain separation from your neighbors. They're also sticklers about the numbers of tents on each site--they'll allow more than one but WILL make you pay for each. Sites are not prepped (no tent pads), and have no fire rings so prepare accordingly.
There is a decent creek (Little Blue) and a pond (Deer Lake) you can fish, but I've never managed to pull anything bigger than a small sunfish from the creek, and I've never seen anyone pull anything at all from Deer Lake, including myself. Deer Lake does provide excellent sunsets across the water though.
Overall, with the free firewood and all of the features to occupy the kids, this place is a winner for families. If they'll start giving campers a little more room and would improve the sites a little, it would be perfect.
We stayed in sites 102 and 104 with 3 other families, and used a total of five 3-4 person tents. We had plenty of [level] room to spread out. Our sites backed up to hundreds of acres of uninhabited forest, while also being within short walking distance of the camp store and visitor center.
Sites were non-electric, and there were no receptacles to be found anywhere close, even at the conveniently located (and very clean) bathrooms. Bring Your Own Electricity, but please note the generator quiet hours. (Solar generators and power stations for the win.) Fire rings are very heavy cast iron with with very sturdy, adjustable-height cooking grates. They really put out some heat once you get the fire going, and are very easy to cook on.
They don't want you bringing in outside wood for obvious reasons, and they only sell compressed saw dust wood bricks at the camp store. They work well once you get the hang of them, don't smoke much at all, and keep you warm. However, at ~$7.50 for a case of 6 blocks, they can get expensive quickly if, like my family, you're the kind of campers that like a good fire.
Overall, park was clean, quiet, and each site has just enough space for you to ignore the people around you if that's what you're into. We love all of the cheesy tourist traps in Cave City, and love the centralized location between Nashville and Louisville--allows me to easily camp with close friends I have in both cities. Already planning on coming back regularly.