I personally chose to just stop using artificial color, cold turkey, and let my natural hair grow out. I didn't want to fool with the lowlights or temp color, as doing so can significantly prolong the growing out process (can take a year or more). I wasn't comfortable with getting a very short haircut--I had long, dark brown hair, and was not ready to change both the color and length too dramatically. So I waited until I had about five or six months of fresh growth coming in, then went in and had the last remnants of artificially colored hair chopped off. At that point, my gray was long enough to try a hairstyle very similar to the one that Meryl Streep wore in "The Devil Wears Prada". Less than two months later, I have already grown my hair out to an attractive, slightly layered, shoulder length style.
I won't tell you that growing out my hair, and having to deal with the two-toned color for a few months, was fun or easy. There were times when I got a few odd looks--but I also got more than a few positive compliments as well. And I am so glad now that I did it. My hair feels better than it has in years! It is so much healthier, softer, less frizzy & easy to style.