Generally speaking, most people opt to simply bring the backsplash tile down to meet the countertop. 4" granite backsplashes are fairly dated, and the cost is usually more than what you would pay for the same coverage in tile. Making a 4" backsplash is labor intensive, and you are still paying the square foot cost of the stone--these two facts drive the cost up. A good tile installer will seal the space where the tile meets the countertop with silicone caulk to match the grout. You should not have to worry about dirt getting in there.

Hi Jennifer, all good points to consider. As a tile and stone showroom I usually suggest to our clients that know they are tiling the backsplash not to have a stone riser. It keeps the look more open and doesn't detract. When we install tile to meet a stone counter we always use a silicone caulk to match the grout color. You're correct about the potential for grout to crack there, it always will at a 90 degree angle. Tell your tile installer to use the silicone and problem solved.