Get a dose of vitamin D at Public Beach. Once you've worked on your tan, hang around and watch the sky burst into different colors as the sun begins to set.
You're spoiled for sightseeing choice in Gatteo. Spiaggia di Gatteo Mare is a good place to start here, but there are many other interesting sights to appreciate. Atlantica Water Park, Grattacielo Marinella, and Levante Park are close to the stretch of coastline and will round out your day nicely.