I wouldn't exactly call O'hana's atmosphere and food "unique" so I guess it's hard to know what exactly you mean.
Satuli Canteen in AK is certainly something I would call "unique." Is it just "not American cuisine and interesting decoration"? There are polynesian themed restaurants outside of Disney and Hawaii (ever been to a Trader Vic's?). You can get Caribbean themed food at Sebastian's, food themed to the countries of the world showcase in Epcot in pretty much every restaurant there (Biergarten and San Angel Inn in particular have an incredible atmosphere), Tiffins/Nomad lounge in AK have a lot of interesting african food, Sanaa in AKL has the savannah view and indian/african hybrid menu, Raglan Road in DS has irish music and dancing as well as irish food.