I used to hike and camp all around the area where Rough Trail 221 intersects with the Nada Tunnel Road or 77. There is an unofficial trail just north of 77 with a giant rock house we used to camp under. Now there is a no camp in rock house rule, which I understand is to not destroy the habitat.
I generally stuck around the RT 221 area and Chimny Top in my earlier years. Mostly because my fellow hikers and I were of limited experience in the way of navigation and gear.
Now we tend to try to put as much distance between us and other people as possible. The rangers can be rather aggressive, and no fun to talk to after I've had a pint of vodka. Plus the easy to get to placed are rather nasty with fecies and garbage.
There are some really nice, less frequented places off of Pinch-em Tight 223/100. On 223/100 mid-way between the intersections of 227 and 226 there is an unofficial trail that goes deep in to a valey with a good stream. This is a great place to go. Lots of good trails and rock formations around. Of corse, I'm not sure if camping is permitted there. (In the black circle in the picture)

Last year we puttered around the loop comprised of Sheltowee Trace on the north (221/100), Buck Trail (226) on the east and Koomer Ridge Trail (220) on the west. It makes a kind of triangle loop. There are some good sites there as the area is about in the center of the reserve.
Any suggestions for a cool spot. Near water is best.