The Ontario Parks reservation site has several photos of each campsite, along with a description and relative quality ratings. While everyone's idea of a perfect site varys, the information in the OP reservation system is fairly helpful.
My best advice for camping at any Ontario Parks campground is (1) yup, its expensive, but well worth it (2) bring lots of extension cord - at least 50' in addition to your 25' or so stock (3) the sites aren't level - make sure you've brought levellers in one form or another (4) there is no on-site water. fill up at the dumpstation on your way in, or use a bucket at a spiggot located throughout the campground (5) reservations are recommended.
