I haven't had to make the decision on whether to have any gray or not....haven't seen any gray hair yet. I'm 48 and have very long dark blond/brown hair. It had red highlights when I was young but they became blond as I got older.
I've always worked outdoors and have always loved the blond highlights I get in the summer. But as jobs changed, I began always having to wear a hard hat or a company ball cap and on my own time I still am always wearing a cap, a motorcycle helmet or a bike helmet. So I began to not have so many natural highlights and also hated the mousy brown it would go in the winter.
So this winter for the first time, I got highlights at the hairdresser. I really like them but now of course I have to keep it up. They are natural looking enough that there isn't a huge root difference when it's growing out.

I really think the blond highlights brighten my face in the winter and they do make me look younger. People often mention I don't look my age.

My age is not something I personally spend a lot of time thinking about but I am realistic about how some people perceive age and how capable they think you are because of it.
I did NOT let anyone know my age at the utility company I work for until I had been there for over a year. Management knew of course as soon as I filled out the papers to sign on for the job but the men I work with didn't know at first. I was already a small sized woman starting in a "non traditional" position as a gasfitter where there had never been one before...they didn't need to know I was middle aged too!