Greece runs on two clocks. There's the one tourists come for — the Acropolis, Delphi, theatres older than most countries — and the slower one the place actually lives by: long lunches, coffee that takes an hour, ferries that leave when they leave. The mainland gives you the ruins and the mountains; the islands give you the light everyone keeps trying to photograph and failing. Athens is the front door, and it has quietly become one of Europe's best city breaks in its own right — grittier than the postcards, better fed than almost anywhere.
What things cost: Greece is mid-range for Europe: noticeably cheaper than France or Italy in the cities, though the famous islands in August charge whatever they like. Eating well is cheap; the big archaeological sites are the main fixed cost. When a zone below says 'low', that means low for Greece.