I actually had the reverse situation. I have reddish/light-brown hair (it gets auburn in the summer but more brown in the winter months) and wanted to get highlights in 10th grade. I told the woman I wanted light brown highlights -- NO BLONDE -- because I thought it looked funny when people with brown hair got blonde hilights. She picked out a BLONDE color and said it would look different once it was actually on my hair -- but no. It was horrible. My hair looked almost greyish from a distance and the highlighted strands felt like straw. I eventually hated it so much that I washed my hair repeatedly with Ultra-Swim shampoo (for removing chlorine) and somehow it took the highlights out almost completely.
I have experimented with sun in as well, but greatly preferred it to my highlights. The sun-in never damaged my hair, and would just make it slightly redder (then again I only used very small amounts). But then again, I was going for more of a lighter-version of what I already had and maybe slightly redder, NOT BLONDE!!! I don't think brunettes should get blonde highlights unless they get their full head done and it matches their haircolor -- too many girls in my jr high had dark dark dark brown hair with a few platinum blonde streaks.
Nowadays I've retired the sun in, but occasionally I use "sheer blonde" shampoo/conditioner by John Frieda and I find that it brings out the red in my hair slightly.
