Although Mykonos has many things to do for a week long holiday, you can actually see the most important sights in Mykonos in one day. This is a pretty frequent case actually, especially for visitors who are coming to the island on a cruise or in a day tour from other islands.
The first thing to do after you get off the cruise ship or the tour boat is head to Mykonos Town, this lovely place with the labyrinth streets and the cosy atmosphere. The cruise ships arrive at the New Port of Mykonos (Tourlos), which is one bus stop away from the city center. The tour boats arrive at the Old Port of Mykonos, which is actually few steps away from the centre of the town.
When you get there, take a stroll around this beautiful place and get lost among paved paths, flowered yards with bougainvilleas, souvenir shops, churches and small squares. The town gets busier at nights when everyone is coming there for the bars and clubs, however it is also a nice place even in daytime.
Make sure your steps bring you to the beautiful quarter of Little Venice, a seaside place with colourful houses right by the seaside and balconies hanging over the water. This is the most picturesque spot in Mykonos. An uphill path from Little Venice leads to the famous windmills above the town, renovated and offering fantastic view to the Aegean Sea. Little Venice and the Windmills are also the best sunset spots on the island, which is why they attract lots of visitors that time.
After a walk around Mykonos Town, it is time to head to the beaches. The island actually has some of the best beaches in Greece, especially on the southern side. For more quiet beaches, head to Super Paradise, Lia and Elia. For beach parties, head to Paradise Beach, Psarou and Paranga. All these places have soft sand and fantastic waters.
There are actually many ways to go to the beaches in Mykonos. A boat departs frequently from the old port of Mykonos and stops in various beaches on the south of the island. There are also frequent buses to all locations around Mykonos departing from Fabrica Square or the Old Port.
Of course, the most fun and easy way to see Mykonos in one day is to rent a car or bike. Bikes are the cheapest option to explore Mykonos in one day and there are actually many bike rentals all over the Town and at the two ports. There are also many car rentals in Mykonos, although for cars it is advised to book online few weeks before arriving at the island. Renting a private means will make it easier to see Mykonos in one day and will give more flexibility to get around.