Tiles are one way to introduce some pops of colour in your kitchen. If you are worried about the grout discolouring, use epoxy grout which is more resilient to liquid staining. Also, if you use a coloured grout, discolouration will be less noticeable. If you choose textured tiles with rectilinear edges, grout lines are almost invisible. Using tiles can look more traditional compared to glass or stainless steel. The problem with stainless steel is keeping it looking good. Drip marks and grease are instantly noticeable. Glass is less obvious when splashed. They are both more industrial and modern looking. What about using the same material that makes up your worktop as the splashback? Most manufacturers of manmade worktops also do an 11mm thick splashback and upstand.

Do you like patterned tiles at all? Doesn’t have to be garish and you can keep the pallet simple. I’m thinking tile the whole wall, the same width as the vanity unit, up to the ceiling, similar to first picture. Or if that’s too much, then just tile the space from the sink to the mirror. I would raise the mirror a little so that it doesn’t get too splashed.

Shutterstock [website] supply high quality images, either photo's videos, AI images etc and they're sold under licence on behalf of the original artist, so there's a massive library of images to choose from so you should be able to see the image before approval. Then the glass is screen printed on the reverse before going through the toughening process, all the glass i've seen which has been screen printed has looked stunning and i'd assume your glass supplier would have pictures and samples of their work [decent sized not little 100mm squares]. Cost wise though your cheapest option would be as Sonia says to go down the laminate splashback route which is a diy option.

Are you having wall units? If so you can have the backsplash up to them. If no wall units then 60cm is plenty enough with maybe a taller bit behind the hob. A picture of your kitchen would help us advise better.