I think it's an interesting idea. My husband and I are from California and never had sweet tea before living in Nashville during college. We were always having to specify that we wanted unsweet tea in restaraunts. Now we both like it sweet too!

Have you been to Hawaii? I strongly suggest doing your research as you should before any big venture. In particular, a customer and competitor analysis will help to determine whether there would be any demand for sweet tea and burgers. It would seem like you couldn't go wrong with burgers, but what would make your burgers distinctive from the rest?