I once flew to SF for a weeklong work onsite and realized as I was going through security that I'd left my phone on my bed at home.

People at work looked at me like I was an alien, but honestly I had a better time in SF than I ever had before, just organically discovering different things as I walked around (which I always do anyways when I visit cities, much prefer walking to trains, and prefer trains to taxis/cars).

Having a good book or two and journal helps alleviate the boredom in a much more fulfilling way. And then just allowing yourself to be bored and sit and think feels good too.