Here's another picture that shows the other side of the room where the existing cabinets/bookshelves are.

I actually like the contrast between the white cabinets and the walnut counters, seems to warm up the cabinets.

Have you considered wood for the desk? It will add warmth to the white melamine. You could either match it to the existing walnut laminate, or if the budget allows, replace the laminate too. Solid wood counters can be surprisingly inexpensive, as long as they aren't made from exotic wood.

Are you near an ikea? I'd probably just do ikea butcher block. If you aren't a fan of the stark contrast, the lighter wood would work great and you wouldn't need to stain the block!

Thanks for the responses! I was actually thinking about a Formica finish called "Black Walnut Timber," but I'm just not sure if it would make the area look smaller than it is.

I haven't considered wood because I always thought it was more expensive. But maybe I should look into it.

I'm not sure about the butcher block because there are very warm (kind of golden) colors in the room with the floor and the paint...

But in any case, thanks for the great suggestions!

On the wood, if you cannot go identical to what you already have, go the very opposite.