We put our Richard - our guitar player who often sings lead - in the middle. I tend to stand on his right because I play a mandolin - the neck is rather short and doesn't get in his way. Our banjo and guitar player David is on the other side - Richards left - where he has room to switch instruments. And since Richard does most of the introductions it helps keep the focus in the middle. I'll add that the only time you'll find me to the right of a situation is when we're standing on stage.