Picking roof color is stressful, isn't it? Personally I'm with your wife on browns, but judging by their popularity it's not wrong. I'm drawn to a blacker roof. I'm 99% sure I went with charcoal but unfortunately it's not specified in my contract because I hadn't picked yet at that point. I was nervous about it being too black, but there is more of a color variation than you might think based on the sample. Here's an example similar to your color in my neighborhood. Several houses around here similar. The fact that you have black shutters makes this look a no-brainer for me.

And another...

And finally, my charcoal. (Bumping up to 99.9% sure)

I just had my roof redone with the Timberline HD Charcoal. It is not as black as I expected it to be based on the sample, which is a good thing. I thought Slate looked too gray. I don't think you can go wrong with Charcoal.

If you're up to it, you could go to Home Depot, buy a bundle of the Charcoal (I don't think they will sell you a few shingles) and lay it on your roof to see the color...

After looking at some houses and foodonastump's photos (thanks!) I'm am starting to lean towards the pewter grey. It's pretty much the same pure grey as charcoal, just a bit lighter. It seems like the grey picks up the black shutters and looks fine. I think Mission Brown (my other choice) would probably work as well.

In the real world, Slate looks way too green for me, at least for our house. A local supplier also recommended Weathered Wood, which works but isn't our first choice.

And so Pewter Grey it is, at least until we change our mind again!

Try some of the color visualization applications that the shingle manufactures have out there.

I prefer the Owens Corning Duration and Certainteed Landmark over the Timberlines by a wide margin as well but that is an unsolicited opinion.