The first decision in Greece is whether this trip is the mainland, the islands, or a bit of both with a ferry you actually have time to catch. Athens is the arrival city for most long-haul flights, and Piraeus, the port, is not next door to the terminal. The mainland has mountains, the Peloponnese, and archaeological sites that are hot and open. The islands are grouped: Cyclades, Dodecanese, Ionian, each with different ferry patterns and different summer crowds.
Greek is the language. English is widely used in tourism, especially on the famous islands and in Athens. Summer is dry, crowded, and the season when ferries are frequent. Shoulder months are kinder and some routes thin out. Island-hopping looks simple on an infographic and depends on a timetable that can shift with wind. Buses on the mainland are useful; trains are limited compared with central Europe.
Cards have spread; cash is still handy for small ferries and island taxis. July and August are heat and peak prices. A week that holds together is Athens plus one island group, or the Peloponnese without a ferry, rather than Santorini, Mykonos and Crete as if they were neighbouring metro stops.
