I have installed Cairo-Dock and Synapse so I have no use at all for the Unity dock and dash.
What more is there to Unity than that? The top bar with the indicator applets I guess. I don't mind it, but I wouldn't mind having another one either.
Can I disable the Unity dash and dock? Or do I need to use a different desktop manager? Which one? The lighter the better. Possibly one that does nothing but display applets in the corner of the screen.