I think I have ridden everything with in 400 miles of columbia and there is not much localy. Carolina adventure world in Winnsboro is a great day trip,alot of mud and technical stuff. Durham town plantation is about an hour outside of Augusta Ga and is great set up with cabins ,rentals but its a go fast place and dirt bikes run the roost there but the trails are very well maintained. enoree trails are a fun day trip at clinton/Whitmire but absolutly no mud,if thats what your looking for. There are several others in Ga,seminole,Broad river but have a ton of mud if thats what your into but Im not.
In the long run I find it a little more costly but some great trails in Tenn and Ky are only 4 hrs away from the upstate and the trails and terrain are endless.
Atv planet has some good links to east coast parks