My sister has never colored her hair and has greyed very gracefully. But it does make her seem older than me - we're only 15 months apart, and I do color my grey. I started getting grey hairs in my mid 20's, and it didn't bother me at all, but then as I got into my early 30's I caught sight of my hair in the rear view mirror one day with my sun roof open and went OMG, I'm going grey! And it's making me look OLD!!!!!
We meet at the gym once a week, and several times when Les has had to work late or been out of town people have asked me where my "mom" is. She has almost no wrinkles, like me, and at nearly 51 years old, a very youthful face. But because I color my grey and she doesn't, people automatically assume she's older than she is and I'm younger than I am. As you can imagine, she hates that. But it does look good on her, she gets tons of compliments on her grey hair, and it's certainly less upkeep than having your roots touched up all the time.
At some point I guess I'll give in to the aging process and go au natural, but I'm just not ready to do that yet. I think the easiest way to go would be to streak in your natural color rather than doing all your roots so it will grow in more naturally.