I'd do a vertical board and batten look on all of it, or a cedar shake look like the Nichia shakes on all of it. Or just keep the stucco look and emphasize the French Country details. No horizontal lines with that roof as they'll emphasize the width of the house and make the roof even more prominent. And I'd reframe that tall section to have the roof "wrap" around it as well. Then do the windows as dormers and add some dormers to the main facade. That takes away from the overbearing roof look and gives additional light to the interior as well. I'm not at all a fan of using something completely different on different sides of the house. It's a look that says "I couldn't afford to do nice stuff everywhere". Even just adding a few dormers will make that roof more charming.

The roof looks like Pewter Gray GAF HD Shingles, (Timberline), the windows were painted - or if those are not, then they will be custom, costing an arm and a leg. The siding looks like Napco, American Tradition, in a Pewter or Silver color - but here are their color choices - you can get around their website through this portal -Napco Trad Lap Siding 5" Colors hope that helps.

Jean, in the rendering below, I matched the siding on your house to the swatches you just posted. I cannot, however, adjust for lighting, so It's critical to get samples and paint them at your site to see what they look like under your actual conditions. Good luck.

I wouldn't go so far as redoing the roof - meaning new rafters and support structure, nor sliding the bay window over. Might as well build a second floor if going to that much trouble. First I would pick a consistent color, either the white of the window or off-white of the gable for all trim. Then I think its a matter of differentiating the bay from the gable end - they kind of blend together with the same siding. So like these examples: The middle white one the bay blends in vertically like yours, but its the same color. The blue and beige houses differentiate the bays from above them. So for yours, the eave bracket detailing is rather simple, so you shouldn't do a lot of busyness. Just adding trim to separate the gable, even carrying that as a frieze board across the top. Adding window head trim (maybe as prominent as a crosshead). Adding a water table trim along the bottom (maybe future full watertable of brick or something). I think I would avoid vertical trim on the bay, to accentuate the horizontalness and balance the skinny verticalness of the massing. I show a window as well, same size as the gable window, if that works in plan. Symmetry forced onto a facade is too contrived, just try for balance. For the porch, can't tell what's going on in this pic perspective but maybe you could just extend the roofline as a shed, maybe the same slope if it works.