Just outside of Florence, the Three Rivers Casino/Hotel has a large parking lot where RVers are welcome to park. The area was clean and nicely maintained. Although it is only dry-camping, it is a good find in an area where there are not many options to spend the night.
Beautiful park, nice management, great amenities as others have stated. However, they have now reached the point where they need to install speed limiters of some sort. There are kids on bicycles in this park that has 10 MPH speed limits, but it is not uncommon to see folks at or exceeding 30 MPH in cars/trucks, since there is nothing to force them to slow down. So be cautious with your walks and your kids here, until they regain control of the speed.