Home/Architect Design Software

punch makes a cheap product for this and they have mac version, you could even use sketchup (I know firms that use sketchup pro)

otherwise you're probably looking at more professional architectural design software such as vectorworks, archicad or highdesign

it all depends on you're level of architectural design experience, if you're more of a novice, sketchup or punch's software is more geared to you as the interface is simpler

hope that helps