I don't know if this will help but it is practical to plot gain vs angle vs frequency in HFSS. This creates a 3D isometric plot.
I recognise that your question was not about HFSS specifically. You can also accomplish a similar plot in matlab. In fact, you can go one more step and plot four parameters where one is color and the other three correspond to the i, j, and k axes. As I recall the command is plot3d and color is one of the additional parameters in the list of arguments that control the details of the plot.
Hopefully this did not stray too far from the intent of your question.