I think the architect's rendering is good, and if you wanted to keep it simple, just paint or stain/glaze the brick a dark slate/black as seen here: http://cdn.freshome.com/wp-content/uploads/2011/05/Haberfield-House-2.jpg or here: http://www.californiahomedesign.com/sites/all/files/wysiwyg/Modern-Dark-IJburg-House-design-in-Amsterdam.jpg . If you want to mix it up a little bit, then I would change a couple things. The limestone needs some balancing somewhere, so if that is important to you, do the stucco, but make the finish very smooth like concrete. I think roof overhang would look better in a lighter color of gray rather than black if you go with the stucco look though. This is a good example: http://www.tazatek.com/wp-content/uploads/2014/03/Excellent-Combination-of-Grey-and-Wood-for-Peninsula-House-Exterior-Completed-with-Modern-Glass-View-Windows.jpg . Also, the bottom set of windows would look more interesting with one big window in the middle with smaller ones on the top and bottom framing it.

I also have a third option as a suggestion. Leave the walls in the same places, but expand the front bottom windows to be floor to ceiling walk-outs. Turn that front area into a wrap around porch with a wood or metal slatted awning that wraps all the way around to the front door. Make the front top half where all the windows are horizontal wood, as you planned, but wrap the wood around the corner on the top half of the wall leading up to the front door. Make the top windows vertical rectangles instead to mirror the walkouts below and to stand out from the horizontal wood. Paint all the brick that remains black/dark gray. (Black brick on the wall with the door and the bottom half of the wall perpendicular to it, and anything framing the walk out windows.) Do a solid overhang at the top of the home as well, but maybe make it smaller than the one the architect rendered? To tie in the limestone, do a bright white door. (If the whole design is too dark and you don't think a white door would balance it enough, I think the black brick could be substituted for the white stucco and the design would still be pretty cool. Add a wire and metal railing around the porch areas and you're all set. I wish I had a program to show what I mean, but I hope that made sense. Here are some pictures of examples of a slatted awning and roof overhang that I think would look nice. http://www.decorazy.com/wp-content/uploads/2013/11/modern-exterior-architect-house-butterfly-chair-glass-overhang-back-view-door.jpg http://media-cache-ak0.pinimg.com/236x/09/2a/92/092a92a651def36498680bd45f3b4d6b.jpg