Mykonos

Mykonos is the Aegean party capital — population 10,000 (locals; 30,000+ summer), the most cosmopolitan + most expensive Greek island, founded mythologically as the rocks where Hercules killed the Giants. Mykonos Town (Chora) is a maze of cubic white houses + bougainvillea + 16th-century iconic windmills (5 white round mills above town visible from sea). Famous as the gay-friendliest island in the Mediterranean (called 'Greek Ibiza'), beach clubs (Paradise + Super Paradise + Psarou), Little Venice (cliffside cocktails for sunset), and Delos archaeological site (UNESCO mythological birthplace of Apollo + Artemis, 30min ferry, world's oldest preserved Greek city). 2.5h ferry from Athens or 30min flight. 1h ferry to Santorini for combo trip.

Iconic Greek + Mykonian cuisine: Souvlaki + gyros (grilled meat in pita, $5-12 — Sakis Grill canonical for budget), Greek salad (with Mykonian feta, $10-18), Lobster pasta (Mykonos specialty, $40-80 — Caprice canonical), Spanakopita (spinach pie, $5-10), Loukoumades (Greek donuts in honey, $5-10), Ouzo aperitif ($8-15), Greek wine ($30-60/bottle).

Bottom line: Mykonos is canonical Greek party + LGBT-friendly + most expensive Greek island. 3 days hits Town + beach clubs + Delos. Pair with Santorini for honeymoon.