The only time I ever reclined my seat was an overnight flight to London. I started out in the window seat and when I pushed the seat back - maybe halfway, if that much - the guy behind me tapped the seat and asked me not to recline b/c he's tall. I was 18 and didn't want to start anything, so I pushed the seat up. Then my dad decided he wanted the window seat - he took some sleeping med to ensure he'd sleep on the plane and not get jet lag - so we switched and the guy did the same thing when my dad reclined the seat. My dad told him he was entitled to recline his seat (it wasn't even close to being all the way back). Then, near the end of the flight, in the morning, the guy tapped my dad's seat again and asked him not to recline it and how he was 6 feet tall and X pounds - my dad, who does not mince words, lol, told him if he needed more space he should get seats in first class.
I think on an overnight flight, reclining seats is perfectly acceptable.