Miami: Los Ranchos vs. The Knife
Good eats much closer to your hotel - Tony Chan's Water Club & Bin 18 276 NE 18th Street (entrance on Biscayne Boulevard). You can also drive or taxi in 5 minutes over the Venetian Causeway to the western edge of South Beach and try Sardinia, Joe Allen's and then the very wonderful Purdy Lounge.
The 2 steakhouses Los Ranchos and Knife are in a tourist-driven marina mall patterened after South Street Seaport. The food will be "just ok" with the Knife offering an all-you-can-eat option and Los Ranchos a "buy 1 get 1 free dinner" weeknights. Bayside Marketplace is designed to squeeze change out of the pockets of cruise ship passengers who get dropped off there by the bus load.
If you hop on the free metromover elevated train, follow the guide to the Brickell loop and just after you puttputtputt over the Miami River, hop off and head to Miami Avenue to try the River Oyster Bar. It's not Old Ebbitt Grill, but a Miami lite version of a freshly shucked shell fish place with VERY good seafood. There is a GREAT honky tonk bar next door opened til 5am called Tobacco Road with live bands nightly (decent burgers, BBQ and chicken wings served til 4am). If you stay there THAT late - TAXI back to the hotel.
For a more traditional seafood setting, Oceanaire is just west of the 10th St Station exit - pricey and very good. There is a PF Chang's at this stop, a Baja Fresh taco shop and a decent light Italian place (salad-y / pasta-y) called Perricone's closer to 10th Street. One block south on Miami Ave is Rosinella Itallian Cafe.
If you ride the Brickell loop to the very end of the line, you will find a few popular spots in the heart of financial district including micro-brew pub Gordon Biersch, fast Med-style food at Pasha's and more pricey (and more popular) steak houses Capital Grill and Morton's. There is a great sundown happy hour out on the water at the Mandarin Oriental Friday nights and an equally popular (much more casual) one at Finnegan's on the River.