Good question! We'd recommend keeping the space open and going with your first idea; low credenza with floating shelves above. From the looks of it, you'll want to extend the cabinet on the right side until you're a few inches away from the door casement. Then mirror that exact width on the other side. You can fill the extra wall space with a nice floor lamp to warm the space up. As for finish, you could go warm like your floors or do a painted system that blends with your neutral walls - maybe a few shades darker? Hope this helps!

Maybe you will find some inspiration in this design of ours.

Custom Library · More Info

Custom Library · More Info

I would go for floor to ceiling units with mirror doors http://sainteriordesignstoronto.com/fire-to-the-rain.html