I'm from Louisiana, and the best way I can describe South Beach is to compare it to Mardi Gras... Everyone should see it at least once in their lifetime.
First the problem with South Beach... parking. If you go to Soo Be when it is crowded (and that is the only time to go there), expect a trial finding convenient parking. Here's a hint... There is a great high-rise parking lot at the intersection of 6th street and US 1. It is only about 2 blocks from the skin...ummm, I mean surf and sun.
The beach and water is some of the highest quality in the area. It is packed with pretty people of all ages. The traffic is horrible, so unless you have a cool car and like to cruise in traffic jams, park and walk the beach. If you don't want the kids to see butt cheeks and nipples, stay at the beach at one of the many family resorts in a surrounding bedroom community.
Otherwise, slip on the flip-flops, and go for a walk in one of the unique places in this world. Soon the curves and bulges all become a blur...then head over to A1A (the street along the beach) and have a pricey, but entertaining, meal (my brother and I ate at Finnigan's. We split a veggie pizza and had a few cold ones, cost us about $25. You could spend much, much more if you wanted to) at the many restaurants along the strip. The best thing to do is get a seat by the sidewalk and watch South Florida unfold before your eyes. Allow at least 3 hours, go when the sun is shining and stay for dinner! The place is really a kick in the pants.