I do a lot of customs with natural-colored hair, so some of my favorite blends are Sunlight/Starlight/Moonlight, Golden Goddess/Mango Tango, Chocolate Pudding/Roasted Almond, things like that.
In my opinion, it works best if you keep the blend one color, but different shades, kind of like natural highlights. I really like Ultravioet/Sour Grapes/After Midnight, and I want to try a blend with Haunted Forest and Nickel.
I don't have pics right now, but if you pm me, I can search around for other previous blends I've used.