Depending on the airline/route, I sometimes prefer to sit in the last row (aisle).
If I have a bit of time for a layover/am flying to HKG, I sit in the back. Though, the chattiness can become a nuisance (CI/AK/KL seem particularly fond of letting the whole cabin hear them, IME), I'm not interested in being toppled by the deplaning scrum either. Sad that I've chosen a seat solely based on the last few minutes (when everyone is standing, mind you) I'm on a plane...
On the other hand, no one would be sitting behind me, thus no passenger would be banging on the in-seat tv or blabbing for the duration.
MS made it a bit tricky, since they used the back of the 773 as a smokers' lounge.