covering gray at temples

I am looking for advice on covering gray in one spot. I have some gray in my hair, but it really only
shows at the temples, right above my ears (I wear a headband to pull my hair back from my face,
so it shows more because of that also). My concern with using a semi-permanent color is that I
understand it won`t cover concentrated gray. I am thinking of trying highlighting, but again, am
wondering if it will really hide the concentrated gray I have at the temples. I like the natural
color of my hair (medium ash brown). Do I have to color all my hair? I don`t really want to. Also,
do I have to use a permanent haircolor? I am also worried about the effect of coloring on my hair,
but I can see the handwriting on the wall, and know I will have to start coloring or go gray! Any
advice?