Normally in March I'd say stick with typical late winter patterns, however as warm as it's been it would not surprise to see some Sulphur's hatching. I'd go heavy with Yellow emergers, Caddis, BWO and small midges for the fish that get hit heavy.
On the SoHo large streamers are ideal for fast deep sections and although the number of fish go down, the size usually goes up. However, doing so without a boat can prove a challenge if they're generating.
March can be great depending on weather. BWO, Caddis, and probably sulphurs. Take a look at The Best Fly Fishing in the Southeast book (shameless plug) for hatch charts, access points, etc.
Also, Mahoneys sports in Johnson city is a great source of info and flies. Call or stop in and ask for Todd. He'll sell you some of his wiggle minnows, too