I didn't have to read all of the other comments to also come to the conclusion that economy class is the one that needs the big idea for improvement. New business and first class cabins are doing quite well.

Having recently traveled transcon in economy on Air Canada, I will say that a good on-demand in-flight entertainment system with many choices is a huge deal. This really makes for a much better experience.

Beyond that, I have no confidence that things will improve. For very long flights, I've often thought about getting rid of the seats entirely and stringing up hammocks 3 or 4 high, like in an old movie showing the crew on a pirate ship.@:-)