Tiny — everything is a 5-minute walk from Piazza Regina Margherita.
Tourist-trap warning: the piazza has places trading entirely on the view. Stick to the named six below and read the menu (especially "fish by weight" pricing) before sitting.
Marzamemi doesn't have a deep café/pastry bench. The flow is: sit on the piazza, granita + brioche, watch the boats. For serious granita, pair with a Caffè Costanzo morning in Noto.
Campisi (or Adelfio) for the take-home bottarga. Spinazza for the lido swim while seniors stay seated.
Best timing for our group: arrive 4–5 PM, beach/piazza wander, sunset drinks at Cortile Arabo or Bar Cialoma, dinner at La Cialoma or Cortile Arabo at 8:30, drive back to Melilli ~10:30 PM. Avoids worst heat and the piazza is at its loveliest. June is lighter than July/August — our trip dates are favorable.
Tonnara di Marzamemi: the historic tuna fishery. You can no longer enter the tonnara itself (used for events). It's a "stand and absorb" stop, not a ticketed visit.
Bottarga: the Campisi family has been making tuna roe in oil since 1854. Vacuum-sealed, fits in carry-on, an excellent take-home. Pasta with bottarga is the Sicilian dinner-party trick.
Beach caveat: Spiaggia della Spinazza can have algae buildup in early June before the lidos do their daily clean. Vendicari Reserve beaches (Calamosche) are gorgeous but require a 1.5–2 km walk in — not for Matt; an adult-and-teen sub-trip option.