Judy,
I can suggest two campgrounds but no RV parks as Marsha and I have typically avoided such.
One is Calhoun Falls SP on Lake Richard B. Russell in South Carolina. It is an absolutely beautiful park, the newer loop only about 8 or 9 years old, though the "older" is only about 12. All sites are paved with large pads and plenty of privacy if that is what someone would want, though I doubt that is our main concern!
There are also plenty of back in and pull through sites as well. To top it off, there is a community building near the other loop that is also only about 10 years old. There are not full hook ups, however, so that might impact some people, but if this is only going to be three days... You can see a picture of one site in my signature and I have many more.
The other is just outside of Buford, Georgia. We have only camped here once, but it is a nice place. It is a Corps of Engineers campground on Lake Lanier called Old Federal. It too has good sites, many of which have full sun. I don't believe I am misrepresenting it to say that it is one of the more popular campgrounds on Lanier. Lamar might be familiar with it.
I am not too sure about reservations at Old Federal early in the season as they only opened up ALL sites July 1 this year. Reservations at Calhoun Falls are on a site by site basis and can be reserved at any time on the South Carolina parks web site. I know the sites like the back of my hand and would be glad to do a list of good sites if everyone thought this would be a campground we might want to pursue.