What fun! I am originally from that area (before moving north to Central FL), and I was in Miami this past September. We actually stayed on Miami Beach at the Radisson Dauville (not the best hotel...but we had no options as the TA for SO's work booked it). The best part was that it was on the Beach and we had an ocean view. Some of the restaurants in South Beach are great. Ocean Drive is directly on the beach and most of the restaurants have outdoor seating on the sidewalk. They have these big displays of their food, and the host tries to thrust a menu on you as you walk down the street. The atmosphere is so much fun. Make sure you walk up and down, and don't miss the sand sculputres, at night they light them up and they are beautiful.
I spent my days either on the beach or shopping. Miami (and the surrounding areas) has some great malls and shopping districts. The Adventura Mall, the shops at Bal Harbour, Cutler Ridge, Dadeland, the Omni mall, and the Galeria mall are all great and most within about 30 min of downtown Miami (give or take depending on the traffic/accidents/whatnot).
Are you doing anything touristy? Miami Seaquarium, Metrozoo, Vizcaya, Monkey Jungle, Parrot Jungle

? Tons of phototaking opportunities. If you love expensive homes check out Star Island they have some beautiful homes.