Go with glass, just keep it neutral with your busy counters.Small mosaic will probably be too busy, unless you go completely neutral.(see first picture) You could also go long and linear glass if you want to have fewer grout lines. (see last picture - this would be the best choice in my opinion.)

I have a simular kitchen challenge. I am looking at clear glass and pure white glass linear 12x12 tiles but they are about $25 sq ft. (Tesora, I think) They won't take attention away from the granite, but will add a zing to the kitchen!

I would not use the small glass tiles either. It takes away from the granite, and makes it too busy. I would look at large porcelain tiles ~ 12x24 and very small grout lines. I have used one from Lowes and it looks great!

subway tiles are timeless

Keep it simple, let the granite be the star, choose a subway tile (timeless) that is not bright white to blend with your granite. Bring home several samples to try in the right light for your kitchen, don't trust the lighting in the store.