Returning to the scene of his salad days, Peter J. Frank encounters a more mature Miami.

I spent my teenage years in South Beach before it became “South Beach”—dancing at roving parties in run-down hotel ballrooms; shooting late-night pool with drag queens at dive bars; scarfing Cuban sandwiches on the sand at sunrise. I mellowed—eventually—but Miami seemed to prolong its adolescence. While the clubs grew slicker and the hotels more expensive, partying remained the point.

The 2008 recession was a wake-up-grow-up call, and in the years since, the city has become more urbane and (dare I say it?) dignified, with a Frank Gehry–designed symphony hall and, of course, Art Basel. A wave of new hotels has rolled in, and more are on the way. But what does it mean to be a grown-up hotel in South Beach?

Two newcomers are trying to answer that question. For the James Royal Palm (pictured; 1545 Collins Ave.; $$$), which opened in November, it means a focus on the local and sustainable. Snapper at the restaurant, staff uniforms, even the plantain chips in the mini-bars are South Florida–sourced. Here, the wood is reclaimed and the beach huts solar-powered. The whimsy can feel a bit forced (lamp cords pinned to the wall in a squiggly pattern; pillows printed with ctrl alt del), but the 393 rooms are large and bright, and nearly half are suites—a boon to families, who will also appreciate the kids’ club.

A few blocks up, the Philippe Starck–designed SLS South Beach (1701 Collins Ave.; $$$$), is the new Miami sibling of the Beverly Hills original. (The company is also taking over the Raleigh.) The 140-room SLS is very much about drinking and spending and having boisterous dinners, but it isn’t juvenile. The global tapas at Bazaar are by José Andrés; the Hyde Lounge is more surf lodge than dance club. Even the interiors are fairly restrained: the baby-pink accents in the Louis XV–style rooms were inspired by Starck’s new daughter.

So one South Beach hotel has a kids’ club, and another has a toddler as a muse. Domesticated? Perhaps. But both of them remember that sometimes adults just wanna have fun.

Peter J. Frank is the director of editorial product development at Travel + Leisure.