The beaches in Argentina are not good. Carilo is the best but the water is the same: cold. Also windy. Huge crowds of people in January. A nightmare and quite expensive. Florianapolis is nice but I agree that it is spread out, you need a car. Also family oriented if that is what you want. Buzios is lovely. Very pretty beaches, warm water. I feel unsafe in Rio but I guess if you stick to the beach of a good hotel and take nothing of value to the beach you are OK. Punta is all about status and showing off. I hate the place. You see the same people from BA that you have seen all year in Recoleta, Barrio Norte and Zona Norte.