Haircolor Dilemma

Hello everyone!! I haven`t posted in a while but still lurk and read.

I have a color question.

Right now I have highlighted hair. It is medium fine and shoulder length. I am trying to grow it out as healthy as possible.I do have some gray I am trying to cover. My natural color is a dirty dishwater blonde now(was white haired as a child) I have been getting highlights for about 10 years.

I am seriously considering going for a more natural one process color that resembles my color with maybe a little red (auburn) thrown in. I have a very light complection and green eyes and am 36 years old.

I am very aprehensive about the color change but want a change in looks without a haircut.
My question is for someone my age, would the darker hair look better? Also anyone that has some gray (about 10%) do the one process colors do better or the highlights as far as covering it up? I have one gray streak in the front at my hairline that very rarely always gets covered with the highlights.

If anyone has any experience with a problem like this, please answer.My appointment isn`t until November 1st.

Thanks, Lisa