It would be a great feature to add additional options to the Geometry Offset command. So when you offset a line you can also change the color, linetype, etc. EX Offsetting a white solid line could create a light magenta dashed line with 6" spacing.
The dhOffset macro does exactly what you have requested. In fact I use this macro so often that I have a custom keyboard sequence for it.
I am not sure if this macro is still available or if I am allowed to distribute it. Perhaps Mark or Nick Pyner may know the answer to this.