I prefer the back because:
1.) I am very tall/large (I'm a bit over 6'05" and built like a linebacker) and people have a hard time seeing around me.
2.) I like to see the whole room, not just up front. That's a personal idiosyncrasy, since I hate to sit with my back to the door in public places. Additionally, I used to be a bodyguard, so it is a habit to be aware of everything that is going on in a room.
3.) If I need to leave for some reason, I don't want to be a distraction.
What I actually do:
1.) I sit within the first 10 rows on the extreme edge so that I won't block the view of people behind me.
2.) I want to set an example for the youth of our church to sit toward the front.
3.) I carry a concealed handgun and I sit in a place where I can take cover and react quickly to threats in the event something like that happens. (FYI, reacting quickly to threats does not mean I just starting firing my weapon like some people assume. Essentially, it gives me the opportunity to quickly assess the threat(s) and move quickly to close the gap and neutralize the threat with the minimum level of force needed.)
What I have done when I was a pastor or preaching in a church with most of the congregation sitting a long way from the pulpit:
1.) Comment on the "great gulf between us" in a good-humored way and build rapport with those who may be sitting a long way off because they don't want to be involved.
2.) If I have wireless capabilities, leave the pulpit and make generous use of the aisles to keep the congregation engaged. I go into the pulpit with minimal notes since by the time I stand up to preach, I have essentially memorized the scriptural passage through study and only need a few items on a piece of paper as a crutch in case I somehow lose my train of thought. I will have my Bible in hand, along with a half-sheet of paper (the notes) tucked into the open page, so I can engage people very directly if necessary.
3.) I DON'T get passive-aggressive about it, but genuinely let people see that I love them and that I am merely working to communicate effectively with them.