Cranberry river is a beautiful area with a variety of fishing conditions available. In the spring Cranberry is stocked every week. So while there will be plenty of fish there will also be plenty of people. Don't get me wrong, you will by no means be combat fishing, but in order to get to waters that are not as spooky you'll have to travel a little further.
The Cranberry Backcountry is a 16 - 18mile stretch of gravel road that follows the river. There are no motorized vehicles allowed except for road maintenance and Conservation Officers. The only access is by foot, bike, or horse. There are plenty of camping spots along the river. There are a few small shelters along the way, but if they are taken there are plenty of campsites you can find.
You can access the road several ways. Either you can go in the upper or lower gates or you can access through Fishermans Trail from the top of the mountain at Summit Lake. However, this trail is about two miles of steep hiking. The payoff is that it puts you smack in the middle of some of the best water Cranberry has. (Disclaimer: I've never been down fisherman's trail. We always come in from the lower gate. Which is five miles from where fisherman's trail meets the river.)
The road is not difficult and you can make it to the Dogway fork of the river in an easy 3-4 hours from the lower gate if you don't pack too heavily. We always ride in from the lower gate about 2-3 miles, camp, then ride another 3-4 miles in the morning and fish our way back down the river to camp. There is a section of the road where the road leaves the river and you climb up the mountain and then back down the other side. But its gradual and if you're in relatively decent shape you should have no problem. Plus its all downhill the other side.
The best part about Cranberry is that you can typically always find a place to camp. If you get to tired to keep riding, explore one of the wooded areas between the road and the river and you will almost always find a fire ring where someone else camped before.
There are plenty of other options in the Monongahela forest but the cranberry is my favorite. I have a lot of childhood memories there. But there is the Williams river, the Cherry river, and of course the famous Elk River. If you choose the Elk you will not be disappointed either. There are a number of lodges that offer guided trips that I recommend. There's a trip report from another member that ill see if I can find.
Hope this helps. Feel free to ask more questions.