I think you could sell things a normal beach gift shop would sell, maybe shells, coconuts, other beach fruits like durians, mangos, etc. Could do maybe a little tiki bar with the coconut drinks, maybe some Hawaiian print shirts, you could even get the shirt stack and make the top shirt a Hawaiian one, so you can display the stack on a table, and maybe have one hung on the wall behind it. There are lots of decorations like the stuff you get from Pascal and the island that would look good. This sounds like a really cute idea! I hope it works out for you~