IMHO I think long grey hair is ageing and inelegant, unless it is swept up in some style or other. frankly if it is worn loose it only looks good if it is thick, well groomed. Depends on face shape too.
Colourwise it depends on the skin tones. I am lucky in that, having given up highlights a few years ago, my now natural colour is being complimented, and it is slowly turning a pretty grey and not pepper and salt and suits my skin tone. As it is getting thinner I am having it trimmed a bit shorter every two months, and layered. Looking as good as it can with older age. I hope.