I would not go with gray, because it will dull down the vibrant blue frame colour. With a "cold" frame colour, I'd suggest either a "warm" handlebar tape, or white. If you are worried about white getting dirty, coat white cloth tape with clear (not amber) shellac. I did this to mine Bianchi and have ridden it several times in absolutely filthy, slushy weather with no fenders. Spray all over the handlebars, but I simply wiped it off with no long-term effects. The clear shellac will make the handlebars look cream, or off-white, depending how much you apply.