South Beach with children is better than its reputation and worse than its marketing, and both halves of that come from the same fact: this is a dense, adult, late-night neighbourhood wrapped around one of the best public beaches in the United States.
Take the beach first, because it is the whole plan. The sand is wide, free, lifeguarded through the day and accessible from the end of every numbered street. The Atlantic here has small surf most of the year, no reef and no coral to cut feet on, and the water is calmest in the morning before the sea breeze fills in. A family that gets to the sand by nine and leaves by noon has had the best of the island and missed the worst of it.
The island's small size is the genuine advantage and almost nobody frames it that way. In most beach destinations a nap means losing the afternoon. Here the room is a ten-minute walk from wherever you are. You can go back for two hours in the heat and come out again at four for the playground, and nobody has driven anywhere. Bring a stroller and the flat, kerb-cut sidewalks on Collins and Washington and the paved beachwalk make it easy.
The parts that need planning are shade, food and the evening.
Shade barely exists between 5th and 15th Street. Lummus Park has palms, which throw a thin, moving shade, and the pavements on both sides of Ocean Drive are exposed. In July and August the middle of the day on that strip is genuinely hard on small children. Bring an umbrella or rent a set, and treat noon to three as indoor time.
Food is the other trap. The sidewalk cafés on Ocean Drive run pavement hosts, menus that sometimes arrive without prices, and automatic service charges, and a family of four can end up with a bill that bears no relation to what they thought they ordered. One block west solves it.
The evening changes character faster here than parents expect. Around nine, Washington Avenue and the southern end of Ocean Drive turn into a nightlife district, with the noise, the door queues and the promoters that implies. Plan dinner early, on Española Way, Lincoln Road or at the quiet southern end below 5th Street, and be back before it turns.