Greece is special in several different ways:
1) The best thing are the picturesque islands with white & blue houses!
2) Incredible bays for swimming during the day!
3) Famous Greek food.
4) Possibility to check a different island every day!
5) Incredibly rich history.
In Greece, in only 7 days you can experience everything you ever imagined. You can check historical places all the time.
When you change your mind you have several party islands, where you can give yourself a TIME OUT!
When you get tired of this you can only go to one of the many incredible bays and relax, swim and enjoy the sea with your favorite book.
After you fill your batteries again, you can go and choose between several different water sports possibilities while all the time you will check one amazing town after another and enjoy great Greek and & Mediterranean cuisine.
Other Greek highlights are better explained by Lonely Planet guides.
You can check all of the info about Weather, Currency, Tips and other info and a lot of other useful info on this link: http://www.lonelyplanet.com/greece