Depends where I'm going - for the most part I haul the bag around. When I'm out working in the field I've got my zip up CLC bag that has anything I need for basic electrical, telecom, repairing/working on computer equipment, and racking gear. I have clip on zip up bags from CLC that have "special" job kits in them. Those I have to know ahead of time - e.g. working on coax
systems. When I'm at the office, it's the office toolbox, sits in the desk
drawer and I tell trusted colleagues its there. I have pretty much everything I need to work on anything in a full scale datacenter in there, and I can pick it up and go with little to no notice.
The bag also fits inside my suitcase nicely and leaves ample room for enough clothing. If I'm on the road
for more than a few days, my suitcase expands from carryon size to taller. Of course with the toolbag it's got to go checked luggage anyways which is a real PITA. TSA opens the damn thing every single time.
No offense, but that thing would get the crap beat
out of it pretty quickly in a heavy use environment. I had one of the Craftsman ones, just the top part. It was nice for small stuff where I needed to take a circ saw and drill or some other small assortment of power
tools. Only use I ever had for it - don't have it anymore. Those plastic handles have a tendency to break too.