Sound and picture are aimed at the center seat in about the fifth or sixth row up in a stadium house (I was manager at a theater and this is what the tech told me), but now they have these stadium houses where you enter halfway up, and I have no idea where they aim it in those houses.
I used to sit in the center, but after I got married, we migrated down to the second row behind the area designated for folks in wheelchairs. My wife tends to fall asleep in every film, and she likes to put her feet up on the rails. If it's a movie that I know will be an experience (i.e. "Transformers") she usually lets me sit dead center.
I love being married.