Matthew, your answer TOTALLY cracks me up. And yet seems to be coming true regarding myself.
And I agree with the other comments I've seen so far...first off, do a search within this website, we've discussed this MANY times. And second, it truly is what you think you need.
I now travel around a lot and like Matthew have many things provided for me. I know of certain harder-to-find office supplies that it's usually easier for me to get myself than try to explain to a runner, so I bring those. I have a "run-belt" that was created for me by a prop guy in Milwaukee that I wear with my Leatherman, flashlights, pocket of sharpies, scissors, etc...and then my personal things, like a rubber chicken lollipop-holder than I bet you not many other people think is an essential thing to have. And then my plethora of light-up toys and Christmas toys (I'm usually on tour during Christmas). And most everything else is provided by the theatre.
Back in college, though, I was QUEEN of the stage management kit...well, a running competition between me and my fellow stage management roommate. Between the two of us we had 3 large kits, and when working together as ASMs would cart them around on a foldable set of wheels and got very good at lifting them together into the trunk of my car.
Make your own decisions. Make them wisely as well as spur-of-the moment. And then constantly change your mind over the next 5, 10, 30 years of your career! And definitely think MacGuyver(sp?)-like in your thinking....what few strange items could I use that can always fix THAT?