My strategy is to use a human-readable password for my guest network (which I actually considered leaving completely open), and a crazy-long random password that I copy and paste from my password manager for my internal network.
I felt like it would make me responsible for monitoring it for abuse.
It could be something as innocent as a cheapskate neighbor using enough bandwidth to run afoul of my cap, or someone using it for nefarious purposes either on a continuous or drive-by basis.
