We went and stayed in Fort Lauderdale, which is a little drive from Miami. There are some really cute restaurants along the main drive that overlooks the ocean, and the W hotel has a great bar.
The Delano hotel in Miami Beach is amazing. If you can stay there, please do... though is very expensive! But if not, you can go and have a drink or two. They have two lounges (indoors and outdoors) and a club. Really awesome!