I just use PowerPoint
I make a grid in metres (you could use feet or yards), and then draw walls, make little doors and windows, have furniture that I can copy and move from room to room, change colours etc.
I use it for trying out office layouts and for house projects. You can import and embed a pre-made plan (scan it and import the image in the background, then draw revisions and retentions over the top before deleting the old image)