Greece has beautiful blue skies, white beaches, ancient monuments and history up to your eyeballs. The people are extremely friendly and many now speak English. Transport systems - whether metro, bus, plane or inter-island ferry - are excellent, though overground trains are still questionable.
The variety of sights is huge, from Athens or Crete's classic ruins to Meteora's pinnacle monasteries, to the lost city of Atlantis [Santorini island, and the apex of pretty Greek islands, Mykonos]. The biggest bargains in the country are ferry fares. Boats are new, well stabilised and fast e.g. getting from Santorini to Mykonos in about 1.5 hours for around €10, depending on sea conditions.