There are so many Islands you can visit in that country and they all have different landscapes to offer. The islands on the west coast of greece as Corfu are known for their huge olive groves and forests, on the Cyclades you find the typical greece white buildings and the island near the turkish coast are almost desert like looking. Additionally you have a lot of historical stuff from the famous old greece era thousands of years ago and a lively capital as Athens.
photo by Reuben Snyder
photo by Alona Azaria
photo by Stavros Marmaras
photo by Pari Comninos
photo by Pari Comninos
photo by Konstantinos Kousis
photo by Björn Hoffmann
photo by Paweł Bykowski
photo by Konstantinos Kousis
photo by Alona Azaria
photo by Björn Hoffmann
photo by Mika Wist
It´s definitely not possible to see all the beautiful places of that country in one visit, so decide which region you would like to see the most. Then take a plane to one f the several airports and rent a car to be as flexible as possible.