The aesthetics of a home theater include how you move about the room. The entry and exit and how that impacts the seating and flow of a room are things that many people don't think about at all. They plan on a 'great seat' in the center, but then the couch doesn't fit and allow them good access, or placement for that prime seat. So, it is great that you are thinking about the layout.
There is no obvious advantage to a door at the back of the theater, but you do want room to move about, as I just said. You want to just not consider how it looks, but how it works once all the furniture and speakers are in place.
I have seen setups where the door is at the front, and that really only works if the speakers are out of the way and can be positioned around a door. So, I think back, or middle, works in more setups. Watch your surround speaker placements so people aren't running into speakers, but I think that having a door towards the back is a better setup for many rooms.
