Combining multiple electrical runs into a single wire
I suggest doing exactly what TechShop does.  They hang conduit in the ceiling, and above each expected workspace area is a 120/240V twist-lock power connector.  From that, a cord drops down supplying power to the workbench. (In their case a 4-outlet box dangle on strain reliefs giving two 120V circuits in an MWBC configuration.)  I have to believe that arrangement is code legal, since the facility is tip-top and generally a class act, and it leases space from Ford. 

You say "warehouse type space" which means commercial rules may apply, mandating conduit not Romex.  Be careful here, conduits can only hold 9 current-carrying conductors (hots or neutrals, except neutrals don't count in MWBCs) before you must derate amp capacity or use larger wire. That's because a stack of tightly packed wires at rating make a fair bit of heat. If I expect to be near limit, I'll hang 2 conduits instead of 1.