As you might expect, the Cyclades are crowded and expensive during high season -- roughly mid-June to early September -- and high season seems to get longer every year. If summer crowds and prices don't appeal to you, visit during the off-season; the best times are mid-September through October or from mid-April to early June. April can still be cold in the islands and winter winds can be unremittingly harsh. Should you visit in winter or spring, keep in mind that many island hotels have minimal heating; find out if your hotel has genuine heat before you check in. Island boat service is much less frequent off-season, and many hotels, restaurants, and shops close for the winter (usually Nov-Mar). Whenever you visit, you'll discover that most hotels charge a supplementary fee of 10% for a stay of fewer than 3 nights. Finally, it's useful to remember that on most of these islands, the capital town has the name of the island itself. In addition, "Hora," or "Chora," meaning "the place," is commonly used for the capital. The capital of Paros, Parikia, for example, is also called Hora, as is Apollonia, the capital of Sifnos. Just to keep you on your toes, Apollonia/Hora is also called Stavri. When you're in island capitals, try to pick up the handy Sky Map, available at many travel agencies; there's a map for almost every Cycladic island. Although the businesses on these maps pay to be included, the maps are quite useful.
Although the Cyclades are bound by unmistakable family resemblance, each island is independent and unique, making this archipelago an island-hopper's paradise. Frequent ferry service makes travel easier -- although changes in schedules can keep travelers on their toes (often on their toes as they pace harborside for ships to appear at unpredictable hours). Hydrofoils, in particular, are notoriously irregular, and even summer service is often canceled at the whim of the meltemi (blasting winds). Still, the growing fleet of catamarans is greatly facilitating travel between the ports of Piraeus and Rafina and the Cycladic islands.
Tip: If you haven't traveled here before, or for a while, here's some good news: you can now buy interisland transport tickets on almost any island. In the past, often you could only by a ticket from one port to the next: Tinos to Paros; then, on Paros, you could buy a ticket to Naxos; on Naxos, you could buy a ticket to Sifnos. And so forth. Ticket purchase is more streamlined now and you can also get many tickets online.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.