I don't think there's much of a front vs rear difference. I did note that in the bulkhead seats the clatter and chatter from the galleys does tend to be audible, so if that's likely to bother you, get as far away from the galleys as possible. Somewhere in the middle of the rear cabin is likely to be quietest (away from the galleys and bathrooms). On the other hand, people snoring around you is pretty much inescapable anywhere in the cabin on overnight flights. The noise didn't bother me because I used ear buds with white noise, as well as eye shades, and slept very well. Bulkhead seats were definitely more comfortable for sleeping and even sitting, and I'm only 5 ft 8. Even my traveling companions (both shorter than me) preferred the bulkheads.