i am looking for a block that will be 'light and airy' and reflect an islandy sort of them. browns, blues, whites. any thoughts?

Check Quilterschache.com.
TONS of blocks there!
You can make the blocks any color you want, don't have to follow what you see on the site

How about ocean waves - lots of half-square triangles though.

I think the colors you choose will be more important than the actual block pattern. Sailboats would be one patchwork block, and maybe appliqued flip flops or palm trees would fit.

Oh Oh Appliqued beach sandals, umbrellas, bikini's, palm trees, fish, seashells and a woody with surf boards on the beach all come to mind. There are many ways to set those blocks and with the raw edge applique method, it would be easier than you think.