This has been a very interesting thread. My take is that if you don't find ALL aspects of flying interesting then some parts of it will bore you.
Flying a light aircraft is challenging because you are operating single crew with no automatics or navigation systems to help with your situational awareness. You are more at the mercy of the elements (generally speaking) and any errors that occur will be down to you, with little influence from external factors.
Flying "air taxi" is challenging because, although some of the above factors have been mitigated, commercial demands and increased safety requirements bring more pressure to bear. On top of this you are completely responsible for all aspects of the operation when away from base and this can be demanding and very time consuming.
Flying short haul turboprops is challenging because you are now required to operate to a strict set of standard operating procedures in an aircraft type far more complex than before whilst operating into much busier airspace time and time again in the course of a working day. Being part of a two crew operation may also be a new challenge.
Flying medium haul jets is challenging because you are now operating a very sophisticated aircraft into equally sophisticated airspace and over much greater distances dealing with more extreme weather than ever before. Decision making and problem solving skills become finely honed and you discover that more often than not people present you with the trickiest dilemmas not aeroplanes!
Flying long haul is challenging because these same demands are placed upon you but in situations where tiredness is a real factor. Basic flying skills may be eroded due to lack of "hands on" but you still fight to maintain the standards you know you are capable of. Even in the cruise you are constantly monitoring something, be it aircraft systems, fuel, the airspace you are in, whose airspace you will be in next, terrain awareness and possible emergency scenarios, suitable airfields should you need to divert, the weather at those airfields, en route weather/turbulence, the well being of the crew, of the passengers - then repeat.
In each of these scenarios there is a certain aspect of flying that is either hugely reduced or negated which is why I say if you don't find all aspects interesting then at some stage you will be bored.
These comments are aimed at the original poster in an attempt to demonstrate that if you love it enough then flying will NEVER be boring regardless of what kind of flying you are doing. I hope they achieve their purpose.
I've waffled on for far too long - sorry
