When there are a gazillion shows on the Strip to watch, it definitely says something when I've watched this show twice. My first time watching KA was back in high school--it was also my first Cirque show ever. We had second row center seats, and I remember wanting to join the circus afterwards. I recently watched the show again with my boyfriend for our anniversary and sat a little further back.
Seats wise, I actually think it's better to sit a little further back because this way you are able to see all the stunts/activity going on in the side towers. When I sat in the front, you had to turn your head around to be able to see what was going on.
I love how interactive and special the stage is. They manage to do so many things with the moving stage. My favorite scene is definitely when they're fighting with the arrows shooting at the 90 degree stage. A lot of the scenes made me hold my breath because I was so anxious. The only scene that is way too slow for me is Love Dance. Otherwise, it's a great great show, and you do get invested in the story and characters!
Go early so you don't miss their preshow!