This is really hard to answer without seeing the space, but here are a few tips to get you started. How do you want the kitchen to feel? What other colors do you have in the adjoining rooms? Your countertops should complement your flooring and of course tie in with your cabinets. You have a lot of options with white cabinets. First consider what look of counters you like. Bold? Busy? Calm and clean? Then find colors in that design that look great in your space and provide the feeling you are looking for. Once you have the counter selected play around with the backsplash. You can go bold or quite and classic. Consider the rest of your home and what makes you smile!

Hi,

I agree with the comment above that it is difficult to advise without seeing the space but thought I'd put my two pence in re the splash backs.

As you mentioned you have a small and narrow kitchen, something to consider would be antiqued mirror or silver leaf glass. The reflection would open up the space whilst complimenting the grey/white colour scheme you already have in place. For a more budget yet similar feel imitation silver leaf can be used to a very similar effect. To add harmony with the counter tops you choose, the background colour of the gilded/antiqued glass can be made to match the colour of the countertops.

I hope this helps a little and gives you some new ideas to think about,

Good luck!

Sam