The key to nice, clean cable management (with, or without conduit) is to ensure you have a path for the wires. Typically, this path would be around the outside edge, and branching out in a controlled fashion (as you see in Brew's picture).
Now, this involves a bit of planning, because you need to make sure the cable will be long enough for the path.
Another importation point, is to ensure all hardware is mounted, or at least in a fixed location, keeping in mind the above statements.
It does not really matter what you use to contain the wires in their path, (working in IT and a hobbyist) I have used both of the solutions, as well as zip ties, velcro, fancy staple-gun staples, pipes, electrical tape, pipe clamps, electrical staples, maybe more, lol...
Personally, I like to see the cables in a nice path, I prefer to not cover them up with conduit, so I usually use re-usable zip ties. Fancy ones that I can screw in place, or something like George's first picture.