We found Hickory Creek Park (COE), on Lake Lewisville, to be a well kept secret. The roads and sites are paved, have electric and water, the park hosts keep the place very clean, showers are large, clean and heated in cold weather, and there is a dump station.
It is located on the west side of I-35, north of the bridge that crosses the lake from Lewisville. A little tricky to find but well worth it!
Campsites are either on the lake or with a view of the lake, especially when the trees don't have leaves. Easy access to I-35, restaurants and shopping.
We camped with a 36' fifth wheel and extra car. Our kids loved that we had a cerfew!