I'd definitely go to japan. I've been there twice through my old high-school japanese class, and it was one of the best experiences of my life. there are countless crazy things that go on over there that one can only dream of.
Plus it's a JDM lovers paradise! and supercars too, if you like that(which I do
)
Of course, Hawaii is a really beautiful place as well, I've seen photos from my parents vacations there, and it looks gorgeous. Just don't know about fun stuff cause I haven't been there personally.
All in all it just rests in your personal tastes dood.