how about keeping the island dark and getting a gorgeous piece of granite that picks up the brown, white and any other color you like? I would also get one with some movement in it.

I love the look of a different color island and I think the reverse idea would look awesome. I've seen that done a couple times while surfing the web for pictures and it looks really nice.

"Nice, contrasting islands" are part of a specific style grouping from the unfitted/cottage/"scullery" ideas.

"Contemporary" usually means of the now, rather than looking backwards or forwards, though it can also mean what was of the now post-WWII, i.e. Mid-Century Modern and its stylistic compadres and offshoots.

The difference between now-contemporary and then-contemporary is that the now is softer and more human. It has some nooks and crannies, mixes of materials, and visual texture. But it's still pretty unadorned.

Is that what "contemporary" means to you? Sleek. Simple. Using more "green" and industrial elements rather than fabric frills, carvings, moldings and pretty little details.

If that's so, I think keeping it simple is the watchword. If you have a differing island it should have a functional motivation rather than a decorative one. For instance, maybe you want a butcher block island top for chopping, or stainless steel for easy sanitizing. Therefore, I think the same cabinets with your nice reclaimed wood piece sounds like a great choice which will give you some variation without betraying your design scheme.

Here are some island ideas.
Maybe they can help you.
~boxerpups

RDB Magazine

Walnut ( I know you are looking at mahogany but maybe
the shape would be interesting for you)

Sophisticated Stone HGTV

Wide Open Spaces blog

English Oak

Decorpad

Huntwood

Walnut Island

Decorating Diva

Beachy Int Coastal Living Magazine

Mikkelson Kitchen

Johnny Grey

Ocean 5

I know this kitchen is not a dark wood with white counter
but I thought the shape of the island showed some texture
and maybe could help you with ideas.

National Post

What are the materials for your white counters and backsplash? That might help us visualize how the island should look... Can you post pics of the cabinet style/finish, counter and splash materials?

Boxerpups, you have outdone yourself!!! Those are some extreme islands.

I've seen designers run the countertop materials over both of the outer sides. This seems very "today" to me.

Here's a Candace Olson:

Here's one done in wood:

Here's one with cool glass inserts:

And Genevieve Gorder just did one with solid surface like the two above. I could only find the HGTV video. The episode was called Disco Era Kitchen. Here's the link:

Here is a link that might be useful: Disco era kitchen episode, island

Here's another wraparound island with a wood top,

Plllog,
You are too sweet.
Thanks.

And here is one more island. I know it is not the dark
perimeter cabs look you are going for but notice how the
granite (white river) goes all the way down the side of the
island. Creates drama in a gentle way. Very unique and
makes me think of your name contemporganic.

~boxerpups

Thank you to everyone for such great comments, photos and suggestions. We are aiming for the "now contemporary", per plllog's wonderful definitions (thanks!). Love the idea of keeping it simple and using some organic/ natural elements. Seems like the best aesthetic is to use same dark mahogany base cabs and go with a light, organic top with some drama (similar to the last photo submitted by boxerpups). Thanks to boxerpups,becckysharp and kathec for some great inspiration photos!

Now to find that one true dramatic counter that will fit well with the rest...countertops are HARD:(