For Sushi Osaka Miami is a good bet, get a reservation. There is also NAOE on Brickell Key.
A great place is motek in Brickell City Centre, brand new location. Another great spot for lunch is Julia and Henrys in Downtown Miami, its a food market type of place lots of good choices.
Garcias is good fresh off the boat seafood, and you should go to either Versailles or La Carretta for lunch one day to get Cuban food. Or try out Cafe La Trova one night for Cuban food (expensive Cuban food it is usually a cheap meal) drinks, music and dancing.