Not too much happening this time of year. Gets busier April/ May. Sites are very much dependent on your experience. Get familiar with NC diving routines and conditions before pushing your experience further/ deeper.
Bigger operators I'd recommend (although I tend towards the 6 packs), and the wrecks for more experienced divers (at least advanced OW & Nitrox):-
Aquatic Safaris out of Wilmington. Wrecks: Hyde, Markham, Cassimir, Normannia, Lobster Wreck (Porta Allegra), City of Houston, John D. Gill;
Olympus out of Morehead City. Wrecks: Papoose, Schurz, Aeolus, Spar, U-352 (at least once), Caribsea, Atlas;
Under Pressure or Dive Hatteras (boat is the Lion's Paw) are the only folks out of Hatteras. Both are 6 packs. Wrecks: Dixie Arrow, British Spendour, Proteus.
Hope that helps some. Let me know what depth you're comfortable with and I'll narrow down the sites (shallower or more technical depth).
Duncan.