This is what I get using Mathematica 9.0.1.
Instead I want this:
I know how to use MakeBoxes, Format and I thought this code would work:
MakeBoxes[(1/2)(expr_), StandardForm]:= FractionBox[ MakeBoxes[expr, StandardForm], MakeBoxes[2, StandardForm]]
But the code above and all variations that I tried have no effect. This has to be automated to get the look I want. My actual application is much more complicated.