Anyone stayed in Riccione? I can't find it listed in RS's Italy guides.

Riccione is near Rimini. Whether you travel from Venice or Florence, you'll usually make a train connection in Bologna. How to Look Up Train Schedules Online gives you the DB train schedule link and tips for using it. The Adriatic beaches are long and sandy and popular with Italians, but Rick finds the modern towns rather soulless; you don't usually go there for art and architecture.

I have spent a few vacations there in youth. Riccione is probably one of the ritziest (and nicest) of those seaside resort towns on the Romagna coast. There is a train station there along the Adriatic rail line between Rimini and Ancona. To reach it from Florence, you need to Bologna first and change trains there.
Those towns were developed for the most part after the 1950s and 1960s (and also more recently). So no medieval streets. Everything is rather modern. But Riccione has some of the best strolling streets (I think via Dante was the main drag where everybody goes to be seen) with restaurants, cafes and fancy shops. The end of June is not super crowded like July or August, but in the evenings you will have a chance to see plenty of beautiful youths walking around with gelato in hand and sporting the best summer fashion clothes on their suntanned skin. That area is called the "Divertimentificio d'Italia" (Italy's Entertainment Factory), so plenty of megadiscos, theme parks, bowling alleys, restaurants, and entertainment galore. It's basically where many Italians (and Germans and now increasingly Russians) spend their summer vacations.