As with any trip, do your research, read your reviews, peruse Google Satellite maps and talk to locals when you can.
Mountwood County Park http://www.mountwoodpark.org/about.html is located about 15 minutes east of Parkersburg on Rt 50. Heading east on Rt 50 from Parkersburg, WV you will arrive at Mountwood County Park on the right...but the campground portion is a mile further east on the left side of the road. Both are marked by road signage...but most would assume they are all in one location.
If you bring your quads, dirt bikes or mountain bikes with you when you camp, then Mountwood County Park is for you. Right off the back of Mountwood are plenty of ATV trails to keep you busy during your stay. If bombing mountain bike trails is your thing, then across the highway from the campground is your dream. If relaxing in a serene mountain or river valley campground atmosphere is what you desire...keep driving east on Rt 50 another 20 minutes to North Bend State Park.
The primitive tent sites ($20 nightly) are less than desirable and more of an afterthought...and I'm being gracious. There is patchy tall grass, dirt and rocks with no leveled areas. And you have to wander a distance to the restroom/showerhouse when needed. You can rent the tiny cabins ($40 nightly) up on the top of the hill if you desire. They were rented and filled during my visit, surrounded with trailers filled with quads (not a bad thing, just not what I was expecting). One of the main ATV offroad trail entrances is a hundred yards or so past the primitive tent sites so anticipate traffic and some noise. There were a few electric/water sites available for RV/Campers but the majority of them were filled.
It does appear that that there are several "long term campers" at numerous sites, as wooden steps and decks are built and attached to the campers. I would not describe the campground as neat and tidy, but fills a need.
The other portion of the county park lies across Rt 50 about 1/2 mile east. This is where you will find a nice 50 acre lake...shaped like a "T" on its side... for short paddles or fishing (no swimming permitted), a solid collection of varied ability MTB trails and a cool, little local WV Oil history museum. Being a bit of a history buff, I was fascinated by the museum...how the local town was created during the oil boon and then destroyed by fire...of an enormous wilderness mansion that sat where the campground now sits. Interesting stuff.
There is a nice dog park if you brought your pooch. Several picnic areas with picnic shelters, playgrounds, and decent shared hiking trails.
As stated, if your main purpose is to MTB or ATV, then you might be contented with Mountwood County Park Campground. As county parks go, Mountwood County Park, itself, is nice and has a lot to offer. If quiet camping is your objective, I would recommend NorthBend State Park just down the road a piece.