I'm mixed on this one. I tend to think that of all the annoying things people do at shows, "being tall" isn't the worst thing and that they should be allowed to stand wherever they want to enjoy the show without being guilted into the back of the room. Though, if you're over 6-4 or so, it's probably better for all involved to move back a bit - unless you enjoy getting the evil eye all night.
I usually stand pretty much anywhere and just make sure that there's no one in my immediate vicinity getting blocked (I'm just over 6').