It has been discussed before and I also often find it useful to hide the selection highlight, especially when evaluating the collisions and object intersections - with selections highlight, the wires are always on top so it makes it complicated. There was a similar request in this thread:
So I came up with a script that will let you toggle the selection: ToggleSelectionHighlight.rvb (1.5 KB)
Your best bet to use it is to create a button, and copy the script text in to Command field between:
-_RunScript ( [paste script here] )
This way it will toggle the selection highlighting and should work even while you are in-command, which I find most useful.
Please note, it works per-display mode, so if you toggle the highlighting in Wireframe and switch to Rendered, it will still show, and wireframe will stay unhighlighted until you toggle it back.
Let me know if that does the trick.