One of best pieces of advice I received for my shop build was from a friend that is a commercial electrician. He asked me about the electrical lay out, where I wanted outlets, lighting, the 2-post lift, welders, other machines that require 240 VAC, etc... I had a general idea, but figured I'd run everything surface mount on the walls, or up and across the ceiling.
He mentioned that from a cost perspective, and to keep it clean to the eye, it's better to trench and drop PVC under the slab and stub up the walls. The distance is a straight shot from the electrical panel to any place, rather than up walls, bending corners, or trying to run up and over that tall ceiling area. (I had to rent a lift to run the conduit and wiring and hang the lighting in my shop. You can see it in the previous pictures.)
So I took his advice, and it worked out great. I ran eight 3/4" runs and four 1" runs, and they all stub up and run into a trough that sits below my main electrical box. I built a small template to keep them aligned when I back filled the dirt. My slab is 5.5" thick, and I stubbed the conduits up so that the couplings are just above the surface of the concrete. The 2" and two 3/4" conduits on the side there head over to the house. One is for power, one if for fiber/CAT-6, one is a spare.
Mark