Right, for me it's easy to keep track in my mind of how the levels work. It would be nice if there was a way to tell Revit default behaviors, like which level is above which. One thing that I haven't been able to do is move or copy walls, windows, plus doors from one level to another. As far as I can tell, Revit will let me choose the base level but incorrectly determines its own "level above" value and the windows and doors don't fit in the result.
In the big scheme of things, a _floor_ within a building or structure could be it's own entity with properties and all, somewhat akin to a room tag but far more sophisticated. Then, instead of using the AutoCadish technique of defining levels by drawing lines on an elevation, the traditional "floor" would instead be a "space" that has a well defined volume within the model (_well defined_ includes more properties than just x,y,z coordinates).