If you are staying a couple of days in Nashville, I would second the 7 Points suggestion, it's a lakeside campground and you can even reserve a lakeside site, but still close enough to downtown Nashville to make for an easy commute to day trip. It's open seasonally starting 4/2. As an alternative, there's a KOA and another campground (Two Rivers) off of Briley Parkway in Nashville, it's adjacent to the Gaylord Opryland Hotel which is a tourist destination in itself with gigantic atriums and also lots of dining and entertainment options along with the Opry Mills mall which is in the process of coming back to life after the horrific flood in 2010, the movie theatre and lots of the restaurants and some of the stores are already up and running.