I have the same natural hair color as Colleen. Not quite blonde, not quite brown....I call it "Dirty Blonde".
My FAV color on my hair is the brown right before black on the charts. My hair doesn't hold only hair dye for some reason so if she uses that color or even BLACK, my hair fades to the right color in a couple weeks and then it's perfect.
I just went bleach blonde a couple weeks ago and I hate it. YUCK! Makes me feel so washed out, and I spent $100 doing it with the highlights and all! As soon as I can I'm going dark again. I have been all the colors that Colleen has been as well...and I LOVE auburn...really pretty on me.
Good luck...I'm not a fan of chunk highlights because I think it's looks fake...I always try to look natural, but go for what you like!