I hike and sometimes run the Catawba Falls trail.  It is, I believe, owned by the Conservancy now.  However, this is in McDowell County where I live.  It has a decent but not too strenuous incline going up and the trail is usually pretty clear because a lot of people hike it, especially with their dogs.  There are several little creeks and streams that you will pass over as well.  I work in Buncombe County but don't live there anymore and wasn't running yet when I did live there.  I'd be interested to read what trails others run in Buncombe, as I may want to try something new.  I like Catawba Falls for running and hiking, but its getting a little "same old" for me because I do it at least several times a month.