I have not stayed at the Ren, but did stay at the Courtyard. The Ren is more in the heart of downtown Charleston and many of the sights, restaurants, shopping, etc. is within walking distance. It appeared nice from the outside, but I don't know about the rooms
The Courtyard (a better than average one I may add) isn't terribly far away, but you're going to need wheels and deal with parking.
If you're flying and want to avoid getting a car, the Ren might be worth it. Plus you could get upgraded.
Hope that helps.