Hey.....Hey...., That's "Mr. Hawaiian tourist" to you.
seriously though, I also have some oversize polo shirts that work well too.
They're just not as much fun to wear. It seems to me that most of the year down here any sort of over-garment draws more attention than a single boldly patterned shirt. I didn't think of it, but the patterns do add a sort of "urban camouflage" element as well, and they're common enough in this high tourist area that they don't stand out in and of themselves.
Now if I could just find a Hawaiian style ninja mask.