I stopped colouring my hair about 15 years ago and haven't regretted it at all. I am totally silver grey -- with the exception of a royal blue streak on the right side of my head! :D
I get so many positive comments, especially from the younger generation. They think it is so cool. So many women have said to me that they wish they had the nerve to put a streak in their hair. I tell them "Go ahead and do it. It's only hair, after all."