Anyone traveling to Greece this summer, please bear in mind it gets very, very hot July thru early September. Temperatures reaching 40 C (100+ F) in consecutive days is common.
Also if you need assistance, look for the Greek Tourist Police. They can be found in the major cities and islands. They will be identified as such on their vehicles and on their uniform. They can speak English and a few other European languages as well.
One last thing: Athens, Thessaloniki and the major islands are great but if you want to see what Greece looks like away from the tourist industry, I recommend going to a small village well away from any major town or city.