We have and have not gotten leis. Now we know to ask for them if we aren't given any. I don't care really, but DD likes to have one.
I have seen a handful of people in tropical attire, not many though. I see no reason not to wear it if you want to. I don't think anyone would consider your look at all out of place. DD 6 just bought a tropical Hawaiian-print sundress and wants to wear it when we go in September.