The strength of Revit lies within its families. The better your families, the more efficient you can work.

I - and a lot of other people, judging by all the tutroials online on the subject - find this to be very true indeed. But mostly this is discussed for parametric wall openings (changing door-widths or window-heights) and less so for your sheet titles or things like your scale-bar:

So I figured I'd create a "smart" scale-bar for the office, so that we can have the same bar on all drawings, no matter to what scale they are drawn to. And this is how I did it.

I first created a new generic annotation family ( R > New > Family, select the Generic Annotation template) and drew the basis for it:
The "0" is static, so I just created a Text there.

Next I created a few familiy parameters so that the text specifying the distance could be dynamically changed.
The parameters are: (all of them are Type, since I want to create Family Types corresponding to the correct scale)

Name	Function
schaal	scale (1:x) of the drawing
n01 - n10	calculated scale-value, where n01=1cm on drawing, n02=2cm etc.
detail	Boolean (Yes/No) to determine whether the scale is 1:50 and above or below that (drawing is considered a detail)
unit	can either be m (meters) or mm (millimeters)
multi	multiplier to calculate either meters or millimeters

The schaal is the only parameter the user can and should change. The rest I have programmed with formulas.

n01 - n10 are calculated by taking the scale, multiplying it with the distance on paper (in mm) and dividing it by multi to determine whether to display the result in meters or in milimeters.

detail is a simple Yes/No: Be Yes (True), if schaal is smaller than 50.

unit is determined by detail. If the drawing is a detail-view, display "mm" otherwise make it meters.

Now it was just a question of creating all the labels.

The last label was the only "interesting" one, because I actually displayed two parameters instead of one:

But that's basically it. I can now create Family Types to suit the most common needs (1:100 for plan views, elevations etc, 1:1000 for the situation, 1:5 for details, etc) and still make it very easy to add extra scales.