Thank you everyone, your thoughtful advice was very welcome. I'm attaching a photo as its all finished. I selected Olive Reserve for the splash back and painted the wall above it the same colour. As its a big room with lots of light and a large window it doesn't dominate. The glass is so easy to keep clean and I love the way it reflects the garden and light. Have to say though some people are stunned into silence when they see it, but as the cupboards and bench tops are quite bland I knew something bright was needed

Have you thought of mirrored glass. We rented a $2 million dollar penthouse and it had a dark grey smoked mirrored glass splash back on both sides of a galley kitchen. It was amazing. So easy to clean as no grout and optically it doubles the size of the room. I could also watch the TV and what the kids were getting up to in the reflection of the mirrors. It works both with modern and traditional applications and cost about the same as a coloured glass splash back. You could just go to a standard hight of an overhead cupboard then put some simple shelving (IKEA) up above it to display a few items on this would save you money on the glass and add some visual interest at eye level. I would also do a black chalk board wall behind the door near the fridge. You can get magnetic paint (Masters) If you do two coats of this first and then the black board paint (found Dulux to be the best) over the top it becomes a magnetic blackboard. I see you have a high chair and your kids would love it. Happy renovating.

Personally, I love white kitchens with mirrors - light and bright....plus your room can look bigger. Oh, and what's more you don't miss out on what's going on behind you.

The issue is the water needs to be evaporated out, otherwise you are going to grow mould in the gyprock behind the splashback. Do not put glass over the top and for the love of god do NOT employ the person who suggested it. They sound incompetent. The splashback needs to come off and be redone. The gyprock needs to be fully dried or replaced.