Ok...A favorite topic of mine! I love black and white with grain. I have cropped and enlarged and pushed film to its max to achieve big grain. I have taken very fine photos and doctored them up with software to add grain. I think the grain gives photos and old, historical and timeless look. Color grain has its place too. As for your third photo, I personally don't like two-color because there certainly aren't two-color historical, timeless photos. I would prefer sepia if anything. But that is just me. Your 3rd pic does display some artistic qualities that you may be looking for. It is visually appealing to see the subject in a warm tone while the background is seperated by cool tones. It gives the person here warmth. In closing, I say if the photo has enough simplicity and qualities to hold it's own with heavy grain, I'm all for it. I think your photos are a good example of a photo that is improved with grain. Here is one of my own where I think grain gave it a "timeless" look. What do you think?