Yea, the MTB scene in Valdumpster is pretty poor. But, it is only a short road trip to quite a few trail systems. Tom Brown/Cadillac, Redbug, and Elinor-Klapp parks in Tallahassee are 90 minutes away if you take HWY84 to 319 in Thomasville. Hannah park in Mayport, Florida is a nice fast/flat singletrack surrounded by palmettos and it is close to Jacksonville. Santos and Barge Canal in Ocala,FL are very popular for a good reason even though they are close to 3 hours south. I have heard of a few good trails in Gainesville but havent ridden them. White Springs, FL has some pine straw covered singletrack that is only about 1 hour south of Valdosta off of I-75. Macon has a few parks and the number of trails increases exponentially the further north you get from Atlanta. Raccoon Mountain, in Chattanooga, TN is 6-7 hours north but worth every minute of that drive.
Check out SORBA even more trail beta, and SORBA chattanooga for some of the best trail info in our area.