I once had your thoughts on aviation, boring! However, if you live close to an airport, it can be pretty cool.
Airports can be cities in themselves. And from a monitoring standpoint, challenging and rewarding.
First, monitoring the aircraft. In my situation, once I invested a little time and thought, I was able to monitor the aircraft ground and controller traffic. Much more interesting when you hear both sides of the conversation.
Second, commercial airports to different degrees have public safety, fire, law enforcement, TSA, EMS.
And one aspect that many people overlook is the airline ground operations along with the operations of the airport itself.
Just at my tiny little regional airport, counting the airband, I monitor 4 different systems and now have dedicated 2 radios just for my airport and aviation monitoring.
Most days monitoring the airband can be rather mundane and repetitive, but as the others have pointed out, there can be some real neat gems out there.