Bring the window down to meet the cupboard. Really lefty47 was right about not drawing attention to it. It is a source of light ,,, so no need to clutter it up. But if you took the colour out and painted the top of the cupbard to match the wall it ceases to draw attention to itself. Just because it is a horizontal space does not meant it needs something put on it. Note- With the cupboard being white, it also draws attention to itself … perhaps take that to the wall colour too and lift the pendant a smidge. So your pendant is the feature there. The cupboard … do yo need it? One way to remove what you are calling dead space is to get rid of the cupboard.

This made me laugh: http://www.theguardian.com/environment/2016/jun/09/seagull-turns-orange-after-falling-into-vat-of-chicken-tikka-masala I couldn't copy the picture, but it's hilarious.

If it is a casual buffet type meal you don't need to go over board on the dinner table. I would suggest a lovely table runner a pose of fresh flowers (not high so that you block peoples view across the table). Some lovely place mats, standard silverware and glasses all set out and a couple of very simple candle sticks - I also love the idea of the mini Led Fairy lights but maybe around the room (perhaps a mirror if you have one in the room). If you have napkin rings or can make lovely napkins shapes out of origami, that adds a little bit of class and perhaps a small chocolate at each place setting. Don't go over board. After all it is the company (and the food) that should be the star of the night and you need to relax as well. Not every decorative piece needs to be on the table.

The all black kitchen looks scary as. Maybe because there's no lightness in there at all.