Sorry, I've been on the trail or working, so here are my late contributions:
1. When on the AT (or other trails with permanent shelters), use your tent and not the shelter. That way, the only person snoring or farting whom you have to worry about is yourself.
In that regard, no matter how much you love each other, sleep in separate shelters, especially if you're on a long hike. You'll like each other better in the morning. Exceptions: if it's really cold or my wife and me, especially if you're reading this now, honeypot. Okay, I know this one is controversial. YMMV.
2. When traveling with a spousal unit or any other person of the opposite gender, go deep into the woods to relieve yourself. If somebody else of the opposite gender is relieving her- or himself, walk a decent distance and wait, staring vacantly into the woods in the opposite direction until that person catches up with you.
3. As others have noted, carry extra food and booze. There's nothing better than passing the bottle (or the pipe if you are so inclined) around as you sit by the fire as the sun sets majestically in the west.
As in,
"Me and my old lady sat and passed the pipe around."
John Denver
4. In that regard, nothing is more edifying to your traveling companion(s) than reaching into the fire for just the right-sized stick and lighting the pipe with the burning end. A Bic Mini just doesn't cut the mustard, emotionally speaking. Not that I'd do that myself, but it sets exactly the right tone if you are so inclined. :-D
Stargazer