Sweet 16th Birthday Ideas?

I think the luau theme is cool. It seems fun and it's an easier theme to dress up for. You could have non-alcoholic Mai Tais, pineapple smoothies and you could add the little umbrella garnishes to add a touch of festiveness to things. The leis are a good idea (the garlands). You could have platters of various tropical fruits set out and you can serve roast pork or teriyaki chicken/beef to somewhat keep up with the them.