In this pic I do not see a amntle and even if you had one I would leave it empty and enjoy the art above it. Not every flat surface has to be DECORATED. I do think you need a much larger lamp on the end table though.

I'd first eliminate the corner bookcase (it's empty anyway) and possibly replace it with your tv (if it will fit there). also consider traditional area rugs once the hardwood goes in, to play up on the clean lines of your craftsman style furniture. a new wall color could easily warm up and soften the sharp contrast between leather and wall colors. as for FP...a traditional FP surround made from wood and mouldings could be great, but, an installation of field or stacked stone (they make lighter weight stone veneer for just this purpose) from floor to ceiling could be beautiful with your craftsman style and would really highlight the line of the ceiling. a lot depends on your budget.