I'm glad you're happy with the itinerary! If you're looking for a closer island to Mykonos and Athens, I’d suggest Naxos or Paros as great alternatives. Both are stunning Cycladic islands, not far from Mykonos, and offer beautiful beaches, charming towns, and a more relaxed vibe than some of the larger islands.
Here’s the updated itinerary with Paros as the new island destination:

Day 1: Saturday - Arrival in Athens

• Arrive in Athens in the evening, check into your hotel.
• Take it easy, explore the local neighborhood, have dinner, and rest for the night in preparation for your travels ahead.

Day 2: Sunday - Athens (Day 1)

• Morning: Visit iconic sites like the Acropolis and Parthenon, and take in the views from the Areopagus Hill.
• Afternoon: Explore the Plaka District, walk through the quaint streets, and stop for lunch at a traditional Greek taverna.
• Evening: Enjoy dinner with a view of the Acropolis at one of the rooftop restaurants.

Day 3: Monday - Athens to Santorini

• Morning: Take a public cruise from Athens (Piraeus port) to Santorini. The ferry ride takes about 5-8 hours depending on the ferry type.
• Afternoon: Arrive in Santorini, check into your hotel, and relax.
• Evening: Head to Oia to watch the world-famous sunset. Enjoy dinner in a cliffside restaurant.

Day 4: Tuesday - Santorini

• Morning: Visit the ancient ruins of Akrotiri (Minoan city destroyed by a volcanic eruption) or take a scenic walk around Fira.
• Afternoon: Relax at Perissa Beach or take a boat trip to the volcanic islands.
• Evening: Dinner with a view of the caldera.

Day 5: Wednesday - Santorini

• Morning: Visit the black-sand beaches like Kamari or explore the charming village of Pyrgos.
• Afternoon: Take a wine-tasting tour at one of the local wineries.
• Evening: Enjoy seafood by the coast at a seaside taverna.

Day 6: Thursday - Santorini to Mykonos

• Morning: Take a ferry from Santorini to Mykonos (about 2-3 hours).
• Afternoon: Check into your hotel and explore Mykonos Town (Chora), with its famous whitewashed buildings and vibrant streets.
• Evening: Watch the sunset over the windmills of Chora. It's a perfect spot to capture stunning photos of the iconic windmills with the sun setting behind them. Enjoy dinner in Little Venice by the sea.

Day 7: Friday - Mykonos

• Morning: Visit the Mykonos Windmills and the iconic Panagia Paraportiani Church.
• Afternoon: Spend some time relaxing at Psarou Beach or explore the narrow streets of Mykonos Town.
• Evening: Enjoy the lively nightlife with drinks at beach bars or head to Agios Stefanos Beach to watch the sunset.

Day 8: Saturday - Mykonos

• Morning: Take a day trip to the nearby island of Delos, a UNESCO World Heritage site with fascinating archaeological ruins.
• Afternoon: Explore more of Mykonos or relax at the beach.
• Evening: Enjoy a lively night out, or go for a more relaxed dinner at one of Mykonos' beach clubs.

Day 9: Sunday - Mykonos to Paros

• Morning: Take a ferry from Mykonos to Paros (about 1-1.5 hours).
• Afternoon: Arrive in Paros, check into your hotel, and explore Naoussa village with its charming streets and picturesque harbor.
• Evening: Enjoy dinner by the sea at one of Paros' beautiful waterfront restaurants.

Day 10: Monday - Paros

• Morning: Visit the famous Parikia town and stroll along its traditional streets. You can also visit the Panagia Ekatontapiliani Church or relax at Krios Beach.
• Afternoon: Head to the stunning Kolymbithres Beach or Santa Maria Beach.
• Evening: Enjoy dinner in Naoussa or Parikia with stunning views of the sea.

Day 11: Tuesday - Paros

• Morning: Take a boat trip around the island, or visit Antiparos by ferry for a more laid-back vibe and explore the caves.
• Afternoon: Relax on Golden Beach or Lageri Beach.
• Evening: Enjoy a peaceful evening dinner at a seaside taverna in Naoussa or Parikia.

Day 12: Wednesday - Paros to Athens

• Morning: Take a ferry from Paros to Athens (about 4-5 hours).
• Afternoon: Arrive in Athens, check into your hotel.
• Evening: Relax and enjoy your last dinner in Greece, savoring the views of the Acropolis.

Why Paros?

• Proximity: Paros is closer to Mykonos (about 1-1.5 hours by ferry) and just a 4-5 hour ferry ride from Athens, making it an ideal choice for your trip.
• Charming Villages: Paros is known for its traditional Cycladic charm, with picturesque villages like Naoussa and Parikia, perfect for leisurely exploration.
• Beaches and Relaxation: It offers stunning beaches like Kolymbithres and Santa Maria, along with relaxed vibes, ideal for unwinding after Mykonos.

This should provide a great balance of beautiful beaches, charming villages, and proximity to Mykonos and Athens! Let me know if you'd like to make any further changes or if you need more details!