Exciting
xcitation, previous post
Flying manual, even at FL370 is NOT DANGEROUS, it is just NOT ALLOWED because it is RVSM airspace, where extremely accurate altitude keeping is required.
The 100 or 200 ft margin that we lazy, easily bored humans would maintain if we tried it for 9 hrs would be unacceptable for separation purposes. That is the reason why we delegate that task to ever sharp, never bored autopilots.
Glider flying would be a good training means to bring home the point that flying is a matter of maintaining attitudes and angles of attack, not something of text on screens, whether your IPhone or ECAM displays. Sure, those screens may convey important information, but the flying thing meanwhile is to keep the nose more or less near the horizon, with the blue sky on the side where your aircraft roof is.
FL370, or whatever level you are flying, should give ample margin for normal flying, if not, you have gone too high. Climbing towards, or starting a descent from level, is not against RVSM rules, by the way, neither is flying manually for a short time, e.g. to trim the aircraft properly.