Photoshop is could work nice for the workflow part of it - magicwand, new layer, fill - easy to change colors later.
However it depends what you want to do with it later on. With Illustrator or Freehand (which I like better) it stays a vector file, while Photoshop will raster it and increase its file size dramatically.
BTW: we use ACAD for it (what happens when the design changes? - export again to EPS/PDF...), but I think smart objects cad progs like Revit, ADT or Archicad should be able to print sections as solid color fill. Am I right here?