Hmm, very strange from what it sounds like that she's only selling half the arena - for now.
Whenever I've been to concerts, i've always known them to let you sit in the best place possible kinda thing. Although, when I book, I prefer to stand. I only sit when there are no standing left.
Saw Kelly live in 2005 on the Breakaway tour and she was AAMAZING. If you haven't seen her before like others have said, you're in for a big treat.
Booked myself tickets for me and my friend for Birmingham, standing. If anyone's going look out for us, we'll be wearing personalised t-shirts saying "Kelly Clarkson makes us stronger" because we're geeks and BIG BIG fans :P