Let's clarify what the flooring is in both rooms. Is there a doorway separating the two rooms? If the flooring is walnut in both areas, are your doors and mouldings painted white?

I have natural, light stained hardwoods throughout. The only divider between the rooms is the curved counter/bar area in the kitchen. I currently have brown painted built-ins and mantle in this room. We are flooring in the den to add a guest room above. I hope to do coffered ceilings and built-ins and a mantle that go up to the ceiling. I cannot envision this with my dark kitchen. I am also wondering if I should have my cabinets in the kitchen antiqued/faux finished lighter. Thanks for your response! (sorry for the horrible camera phone photo.)

It is looking pretty dark in that room. I think I'd paint your upper cabinets in the kitchen white, or possibly the uppers and lowers in part of the kitchen. Since I can't see all the kitchen, I'm not sure.

Then I'd consider doing a stone or tile fireplace with white built-ins adjacent to it. Or the fireplace could have a white mantel and surround with dark tile around the fireplace opening.