The blue is awesome (grey is too trendy)! The reason it stands out to you is perhaps because it's the only real colour there. Bring in the blue in a window treatment, a small appliance that sits on the counter, a pretty tray or area rug. Also, it is more appealing often if there are more than 2 colours - so right now you have a white and blue colour scheme - bring in red or orange or fushia - something from the other side of the spectrum (like you did with the yellow flowers but in a more permanent way)!

I'd do the island black but not the overhead cabinets.

Black and yellow are both very strong colour choices and I feel you'd be sick of them before it was time to change them. Black also shows marks more than you'd think. Clear is fine, but have you considered a piece of art behind clear?There are several companies that do this, imageglass.co.nz had one with tuis in it which has black and yellow. As for size are you having a range hood? If so this might affect your choice of size.

Which would look better tiles or glass and what colour? Would it be best to cover the whole wall, half wall under the range hood or just between the range hood and cooker?