Wow, you have good tickets! I have never sat in the terrace section, either. Should be interesting. My Kissin seats are in the lower balcony in one of the first couple of rows. For once, I bought tickets way, way in advance so had no problem getting good seats. I don't like to sit on the main floor because someone tall always sits in front of me and then you know how it is...you're out of luck. For Perahia I was in the balcony but higher up. I did have a direct view of the piano, though, and could clearly see his hands and feet.
And I am about ten miles from you. We may even (gulp) know each other.