You almost need to go dark because there are too many materials and colors already. I would use a dark walnut or dark moss colored stain. I would probably just do a solid color stain for better coverage. I wouldn't pick the railing or anything out. I would prefer that particular window be muted as well if possible with plastic or auto body paint (it doesn't need to contrast the stain or match the other windows). A very dark natural neutral stain will help anchor the house and compliment the other materials/colors. Good job!