I agree crisp white and a change of handles would look great. Also a industrial grey would look amazing, especically with the exposed hardware. Obviously this all depends on the rest of your kitchen but you could be more extreme and apply something cheap like chipboard to the back and apply some fun wallpaper to make more of a feature of all the items that you will have on display.

Dear Azfar, I think your units are lovely, very sophisticated and much nicer than white. Your units and work tops are very similar to those I have in my kitchen, which also have black granite tops. I also have a wooden floor of a similar shade, please don't change this, it is lovely. I was aware when I had my kitchen fitted that the units appeared darker than in the showroom but this was due entirely to the colour of the walls they were installed on. To lift the units, and celebrate their beautiful colour, you should paint your walls a darker and contrasting colour, I have chosen a really shocking pink, Rock Candy, but there lots of options. The showroom I saw my units in used a burgundy colour, too dark for my Victorian kitchen. There are so many colour options which don't have to be expensive, play around with a few tester pots and see which you prefer. This is by far the cheapest option, and I'm sure you'll fall in love with your kitchen units again once your units are allowed to stand out. Incidentally your unit colour helps to visually integrate your stainless steel 'fridge, another reason to stick with it. If you want to add units in the future you could pick up on your new wall colour for a very stylish look.

Presumably by "granite sink" you mean the man made Silgranite type in an inset style which can be used with work tops that are not solid, ir laminate? as opposed to an under mounted bowl that can only be used with solid surfaces as the cut edge is showing... in that case I would go for the Brown as opposed to cream, I think it would look more seamless and classy, also more practical, I know the light colours are not meant to stain but that would be my concern! If you do go for more expensive solid work surfaces then I would take advantage of that and have an undermiunt, and I think these may also be available in Silgranite material and have drainage grooves routered in but with a recessed surround as this prevents water going the wrong way.

I personally would not choose black curtains. I prefer curtains that are a similar colour as the walls, so if you paint the walls grey, then have simple linen-cotton curtains In grey. I cannot see the sink window, so can you share a pic of that wall? I’m thinking, without seeing the window, white painted wooden Venetian blinds. My eye is drawn to your lovely antique style wall clock, so how about a similar shade on your walls, a shade of parchment? If that’s too country style, then maybe off white walls?