Have you considered a quilt pattern that will feature them? Maybe something like Atomic Starburst by Violet Crafts or a shadow box or window pane pattern?
I know when I was able to knit I would hoard hand dyed yarn until exactly the right pattern came along to show it off. I liked socks best-- who doesn't need more socks? But a cowl or scarf would let the colors be shown off too. I loved pairing a hand dyed yarn with a solid to really emphasize the color changes in the yarn.