I would think cream . If you go onto a website such as daft.ie of myhome.ie and look at houses for sale, pictures of kitchens ...I know you could be there all day but I did come across a house in coachford in cork with grey flooring and cream wall tiles ...units and white though but it looks very well
Have you thought about a backsplash that matches the kitchen floor? And then maybe blue walls? It is hard to give advice when I can't see the colors there are so many shades of grey.. (I crack myself up sometimes) If you stick with neutral or earthy tones chances are they will complement each other. If you want to sign up for the BHG website they offer themes for ideas. Www.bhg.com sing up for free and go the to decorating gallery.
I think a brick red or a plum would look great with a grey floor