I can't say I'm ever bored on a tour.
Agreed. There's not a heck of a lot of time for boredom to set in. And if it does, it might be saying something about your tour.
I generally bring a book with me on tour, one that I intend to read, yet rarely do I ever open the cover. Yeah, I probably shouldn't bring with me next time...
Even on my off days, I find little time to be bored. I'm usually consumed with restocking needed supplies, finding out information, getting bike repairs, etc. If I have time left over to do nothing, it's just nice to "do nothing" for a bit.