The hotels directly in downtown Miami are the closest to the port (less than a mile or two). South Beach is neat if you are into the art deco and don't mind paying extra for it. South Beach is farther away than downtown Miami though. So if you are going for location, I do a search on Travelocity or similar search engine to see what is located in the downtown area. I believe there is a Hilton and an Intercontinental (both not the cheapest places). But I am sure there are others that aren't coming to mind at the moment.