In Ljugarn you can have your tent very close to the shore. Nice and family friendly place. Service house is old but it's kept clean. Very nice and friendly atmosphere. Kids liked the pool a lot! Nice rauk (gotland stones) area close by.
Our gnomish friend loved the camping a lot. We went there with a tent and the campspots were great. The facilities are a bit simple (near the tents) but when you walk a bit further there are better quality toilets. Sadly the shower temperature wasn't adjustable.
The nearby beach is perfect for swimming if you don't mind the cold sea...