I ran into this problem, where I imported a file created in another program, and I needed to scale it to a specific dimension. For instance, the drawing was something like 2.64" tall (y-axis) and I needed it to be 4" tall. It is a complex 2d sketch, which I prefer not to recreate.
There is a scale by factor tool already, and this is currently the only option for changing the size of my sketch. I have to calculate the scale factor (4/2.64 = 1.5151) which got me to 4.001" (close enough for this drawing).
A more elgegant solution would be the option to scale the drawing right to 4" in height, and of course the width would scale proportionately. Additionally, being able to scale the width and have the height scale proportionately would also be nice.
If you are wondering, I also tried to scale this sketch by setting a dimension between the lowest Y-axis point and the highest Y-axis point, but received an error that the sketch was over-defined. If you would like to see a screenshot of the sketch in question, please refer to this thread: http://forums.autodesk.com/t5/sketching-sculpting-modeling-and/scale-to-an-exact-dimension/td-p/5562...