My tours usually involve flying or Amtrak, so being able to install and remove the pedals is useful. My pedal wrench is an old Park model that's been discontinued; similar to the current Park HCW-6 headset wrench, but smaller. It's about 6" long, flat, and weighs less than 3.5oz. Give the size and weight, there's little reason to leave this tool behind.

Derailleurs don't need adjusting often enough that it's worthwhile for me to memorize the adjustment sequence. A half-sheet of paper only weighs a few grams and frees up my brain cells for other more important clutter If the paper gets wet or lost, I can figure out what to do just by looking at the components; it just takes a little longer.