If it's a play, I really like sitting in the very front row, center. I like seeing the actors up close. Also, in the front row, I can stretch my legs.

If it's music, it depends on whether it's a soloist or a band. If it's a solo player, or maybe a duo, with no amplification, I'd go for front row. If it's a larger band, or if it's amplified, I'd prefer to sit a few rows back.

If it's a movie, somewhere near the middle of the theater would be best, as long as there's no one sitting in front of me. I HATE IT when people in front of me stand up as soon as the credits start to roll. I like to read the credits. So as a practical matter, I tend to choose a seat halfway back, as far as possible to the left or right, next to the wall. In this position I am least likely to have my view blocked by people in front of me.

Also, I'm tall (6'4"), and I try to be considerate of other people, so I try to choose a seat where there's no one sitting immediately behind me. My wife tends to forget this, so if she leads the way and chooses the seats, she often chooses a seat right smack in front of another couple. Many times, I've sat down and the people behind me immediately get up and change seats. This embarrasses me, so I try not to let my wife choose the seats.