Re: another "which one is better for us?" thread: H25, Catalina 25, S2 28...
I too have a boat on Lake Norman where I learned how to sail three years ago. I sail a Hunter 28.5 that I purchased in Oriental NC and had her hauled to LKN.
I would recommend buying the biggest boat your budget can afford as you will quickly grow out of a boat if its on the small side.
Out of the three boats you mentioned, I would look the hardest at the S2 as you will want the space if you are camping out over the weekend. Also, the bigger boat will be more comfortable riding through the waves created by 36+ ft. power boats going by you during the summer months.
Where are you looking to dock the boat? I have docked my boat at three different marinas on the lake and can give you some pro's / con's with different marinas that you are considering.