Shenandoah is good for training. I have pioneered (in the minor sense) a few new routes there... a little steeper than the trails Like the north ridge of old rag in the winter... Has some good scrambling and maneuvering. The most elevation change you will find south of NY is right around old rag and hawksbill. The combination of old rag, cedar run, hawksbill, and whiteoak canyon in a day has always been a favorite challenging link up. Great to hear you have an old mtb if you will head down this way. Patapsco has amazing single track riding. Also there is usually great riding around some of the local resevoirs and other state parks. PA is also good, but a reach if you are not riding much right now. Sugarloaf mountain is fairly local, I have done as a long bike ride from clarksville (not feasible from aberdeen) but has some good toproping. There are a lot of local little crags in central maryland. Annapolis rocks near fredrick has good rock climbing. The ridges of the Appalachians run pretty flat. I try and mix up my activities for training. Aerobics such as trail running and mountain biking have been really key around here. I gotta run its my nephews bday... Ill keep you informed about local places if you need it.